Max-Planck-Institut fur Physik komplexer SystemeDresden, Germany

Symposium on

Electron Transport on the Molecular Scale

Dresden, 23–24 February 2001

Scientific coordinators:Gianaurelio Cuniberti, Giorgos Fagas, and Klaus Richter

Max-Planck-Institut fur Physik komplexer Systeme

PROGRAM AND ABSTRACTS

Max-Planck-Institut fur Physik komplexer Systeme,Nothnitzer Str. 38, D-01187 Dresden

tel.: +49-(0)351-871-2107 / fax: +49-(0)351-871-2199transmol@mpipks-dresden.mpg.de

http://www.mpipks-dresden.mpg.de/∼transmol

An old image of Dresden

(the Frauenkirche from Rampische Straße)

Molecular electronics dates back almost three decades and is cur-rently an active field of interplay between fundamental and appliedresearch. This development is driven by both the interaction ofchemical with solid state physics and possible technological appli-cations. Recent experimental breakthroughs of conductance mea-surements of single (bio)molecules have given new momentum tothe idea of using molecular-scale active components in electronicdevices. This symposium provides an overview of the present state,current research activity, and future directions in theoretical andexperimental aspects of molecular electronics. The symposium in-cludes, among others, the following topics:

• coherent and sequential transport, tunneling and electrontransfer, contact effects

• description of electron transport via semi-empirical, self-consistent, and first-principle approaches

• realization of molecular scale devices, properties, and func-tional molecules

• break junction, STM, self-assembly, and other common ex-perimental techniques

Contents

Scientific Program iv

Invited Talks

Jean-Philippe Bourgoin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1Roberto Cingolani . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-2Hans Deppe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-3Torsten Fritz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-4Avik Ghosh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-5Bernd Giese . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-6Frank Großmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-7Peter Hanggi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-8Elisa Molinari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-9Abraham Nitzan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-10Danny Porath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-11Herbert Scholler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-12Jose M. Soler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-13Andrew Turberfield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-14Heiko Weber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-15Sophia Yaliraki . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-16

i

Contributed Abstracts

Christoph Bruder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1Lucio Colombi Ciacchi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2Gianaurelio Cuniberti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3Francesca De Rienzo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4Giorgos Fagas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5Dmytro Fedorets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-6Rafael Gutierrez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-7Walter Hofstetter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-8Andreas Isacsson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9Sihem Jaziri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10Ivan Kondov . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-11Paul Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-12Lyuba Malysheva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-13Volkhard May . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-14Jose Luis Mozos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-15Tomas Nord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-16Monica Pickholz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-17Jan Richter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-18Elisa Molinari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-19Reinhard Scholz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-20Gotthard Seifert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-21Sven Stafstrom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-22Jorg Stephan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-23Michael Torker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-24Karsten Walzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-25Edward Zenkevich . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-26

Practical information 1

List of contributors 2

List of participants 4

ii

SCIENTIFIC PROGRAM

Friday, February 23

08:50 - 09:00 Welcome address: Peter Fulde (director of Max-Planck-Institut PKS)

09:00 - 09:35 Jean-Philippe Bourgoin (Saclay, France)Experimental investigation of metal-molecule(s)-metal junctions

09:35 - 10:10 Danny Porath (Tel Aviv, Israel)Towards DNA nanoelectronics?

10:10 - 10:45 Jose M. Soler (Madrid, Spain)Electronic properties of DNA from first principles

10:45 - 11:30 — Poster Session & Coffee —

11:30 - 12:05 Hans Deppe (Dresden, Germany)From Micro– to Nano–electronics: AMD Dresden’s contributions

12:05 - 12:40 Roberto Cingolani (Lecce, Italy)Electronic devices based on DNA basis

12:45 - 14:00 — Lunch —

14:00 - 14:35 Elisa Molinari (Modena, Italy)Electronic structure and transport in guanosine nanoaggregates

14:35 - 15:10 Heiko B. Weber (Karlsruhe, Germany)Experimental investigation of electronic transport through a singleorganic molecule

15:10 - 15:45 Avik Ghosh (Purdue, USA)Ab-initio description of current conduction and surface potentialmeasurements in molecular conductors

15:45 - 17:00 — Poster Session & Coffee —

17:00 - 17:35 Bernd Giese (Basel, Switzerland)Long distance electron transport through DNA molecules in solution:

the charge hopping mechanism

17:35 - 18:10 Abraham Nitzan (Tel Aviv, Israel)Inelastic effects in electron transmission through molecular junctions

18:10 - 18:45 Sophia N. Yaliraki (London, UK)Structure and transport in binary self-assembled monolayers

v

Saturday, February 24

09:00 - 09:35 Peter Hanggi (Augsburg, Germany)Nonlinear electron current through a short molecular wire

09:35 - 10:10 Herbert Scholler (Karlsruhe, Germany)Analogies between molecular electronics and quantum dots

10:10 - 10:45 Torsten Fritz (Dresden, Germany)STM/STS investigations of epitaxial organic thin filmsordered thin films of aromatic molecules on single crystalline substrates

10:45 - 11:30 — Poster Session & Coffee —

11:30 - 12:05 Frank Großmann (Dresden, Germany)Elastic and inelastic electron transport in nanosystems

12:05 - 12:40 Andrew Turberfield (Oxford, UK)Self-assembly and a molecular machine made from DNA

12:45 - 14:00 — Lunch —

Socials

Thursday, February 22

19:30 - get-together buffet (MPI-PKS)

Friday, February 23

20:00 - conference dinner (Sophienkeller, Taschenberg 3, Dresden)

Saturday, February 24

afternoon self-organized sight-seeing/discussion

vi

INVITED TALKS(in alphabetic order of the presenting author)

Jean-Philippe Bourgoin

Experimental investigation ofmetal-molecule(s)-metal junctions

Jean-Philippe Bourgoin

Departement de Recherche sur l’Etat Condense, les Atomes et les Molecules,Commissariat a l’Energie Atomique, Saclay, France

jbourgoin@cea.fr

In this talk, I will first review the various possibilities that exist for preparing metal-molecule(s)-metal junctions. I will then focus on the metallic break junctions techniquethat we used as electrodes with a nanometer scale adjustable gap to contact self-assembledmolecules of bisthiololigothiophene. Finally, I will present recent results obtained by STMon bisthiololigothiophene and bisselenololigothiophene molecules inserted in a matrix ofdodecanethiol.

I-1

INVITED Jean-Philippe Bourgoin

notes:

I-1 (notes)

Roberto Cingolani

Electronic devices based on DNA basis

Roberto Cingolani

Nanotechnology Research Group, Istituto Nazionale per la Fisica della Materia (INFM)and

Dipartimento di Ingegneria dell’Innovazione, Universita di Lecce, Italyroberto.cingolani@unile.it

We have developed a new class of solid-state planar electronic devices in which self as-sembled films of deoxiguanosine molecules (a DNA basis) are used to connect metallicnanocontacts. The control of the selforganization of the biomolecules, results in solidstate biological films with clear semiconducting properties at room temperature (energygap about 3.3 eV) and on short length scales (about 120 nm). These films are depositedon nanopatterned gold circuits having gaps betweeen 1 µm and 30 nm.The operation of the planar devices depends on the relationship between the characteristicself organization length of the biomolecules and the physical size of the metallic gap. Nar-row gap devices exhibit a clear diode characteristic at room temperature. Devices havinggap comparable to the self organization length, exhibit clear metal/semiconductor/metalI–V characteristics, with photoresponsivity as high as 1 W/A. All the devices have negligi-ble aging after several hundreds hours of operation, and exhibit an intriguing temperaturedependence.The impact of self assembling, dipole formation and ordering in the molecular films, onthe physics of the devices will be addresssed in detail.

I-2

INVITED Roberto Cingolani

notes:

I-2 (notes)

Hans Deppe

From Micro– to Nano–electronics:AMD Dresden’s contributions

Hans Deppe

AMD Saxony Manufacturing GmbH, Germanyhans.deppe@amd.com

The microprocessor business has become a main driver of advanced semiconductor tech-nology. It is characterized in unit and revenue terms by a production output of about 135million units in the year 2000 and about $33 billion worldwide and is expected to growto more than $41 billion in 2002 (Gartner, IDC). The trend to increasing more powerfulperformance features - clock frequency is only one of the key parameters - continues andis demanded by the market.

This paper will discuss the necessary prerequisites to a successful microprocessor business,which are leading edge capabilities, expertise and superb execution in all of the following:

• microprocessor design (architecture, product engineering);

• process technology (leading edge development);

• manufacturing and factory capacity (at leading edge in high volume).

This paper will focus on the technology (developed in partnership with Motorola) andmanufacturing. Details of AMD’s leading edge technology which includes

• 0.18 µm 6level Copper interconnect metallization,

• transistor gates well below 100 nm,

• SOI readiness,

will be presented.

I-3

INVITED Hans Deppe

notes:

I-3 (notes)

Torsten Fritz

STM/STS investigations ofepitaxial organic thin films

Torsten Fritz

Institut fur Angewandte Photophysik, TU Dresden, Germanyfritz@iapp.de

In the talk we will summarize the results of several recent studies aimed at design, prepara-tion and characterization of artificial organic superstructures, starting from highly orderedorganic monolayers and ending up with systems prepared by multiple organic heteroepi-taxy.As we aspire to create molecular layers with ‘perfect’ order, we employ organic molecularbeam epitaxy (OMBE) to grow single crystalline lattices of different molecular materials.Having future applications in mind, we deal with organic dyes, characterized by an ex-tended p-electron system which gives rise to a strong and selective light absorption, andadditionally gives a flat molecular shape of the molecules, therefore making them suitablecandidates for building up well-ordered molecular arrangements on single crystalline sub-strates. As a key requisite suitable substrates must provide not only sufficient planarityat the atomic level, but also support both characterization techniques and prospectiveapplications by sufficient electric conductivity. Those desired properties are featured bysingle crystalline noble metals.In addition to a taxonomical grammar of organic-inorganic epitaxy which will be presentedin the first part of the talk, we will discuss in detail the results for two archetypal organicmaterials, namely perylene-tetracarboxylic-dianhydride (PTCDA) and peri-hexabenzoco-rone (HBC), on Au(111) and Au(100) surfaces.

I-4

INVITED Torsten Fritz

notes:

I-4 (notes)

Avik Ghosh

Ab-initio description of

current conduction and surface potential

measurementsin molecular conductors.

A. W. Ghosh, P. Damle, T. Rakshit, F. Zahid and S. Datta

School of Electrical and Computer Engineering, Purdue University, USAghosha@ecn.purdue.edu

Several experimental groups have recently reported measurements of the current-voltage(I–V ) characteristics of individual or small groups of molecules. The problem of calculat-ing the I–V characteristics is very different from the usual problems of quantum chemistry.Firstly we are dealing with an open system having a continuous density of states ratherthan an isolated molecule with discrete levels. Secondly the molecule does not necessar-ily remain at equilibrium or even close to equilibrium - two volts applied across a shortmolecule is enough to drive it far from equilibrium. The purpose of this talk is to describea straightforward but rigorous ab-initio and self-consistent procedure for calculating theI–V characteristics. A number of researchers have addressed this problem, but whatdistinguishes the present approach from previous works is its close coupling to standardquantum chemistry programs like Gaussian. This not only makes the procedure simplerto implement but also makes the relation between the I–V characteristics and the chem-istry of the molecule more obvious. We use this procedure, in conjunction with a rigorousmodel for the contact self-energies, to obtain I–V characteristics for several molecules.The experimental results for phenyl dithiol are in good agreement with the calculatedresults without any fitting parameters except that the overall magnitude is smaller due toless than perfect contacts. The qualitative features of the I–V depends on contact prop-erties such as the location of the fermi energy with respect to the molecular energy levels.Surface potential measurements on self-assembled monolayers (SAMs) of molecules yieldsinvaluable information about such equilibrium properties. In the last part of the talk, Iwill discuss recent surface potential measurements on SAMs of alkane and aromatic thiolmolecules, and our current theoretical understanding of such measurements.

I-5

INVITED Avik Ghosh

notes:

I-5 (notes)

Bernd Giese

Long distance electron transport through DNAmolecules in solution: the charge hopping mechanism

Bernd Giese

Department of Chemistry, University of Basel, Switzerlandbernd.giese@unibas.ch

Experiments on very long distance charge transport through DNA raised a controversialdiscussion in the last years [1]. Today, there is no doubt that transport of a positive chargeover 50 A and more along DNA in water is possible and that it occurs via a multistephopping mechanism [2]. If the positive charge is injected into a guanine base, all guaninesact as charge carriers. Because of the strong distance influence on the charge transfersteps, DNA strands with long adenine:thymine sequences can also involve adenines ascharge carriers [3]. A prerequisite for this mechanism is that the electron transfer is fasterthan the water trapping reaction of the guanine radical cation.

[1] M. Ratner, Nature 397, 480 (1999).

[2] B. Giese, Acc. Chem. Res. 33, 631 (2000); G. B. Schuster, Acc. Chem. Res., 33, 253(2000); C. Wan, T. Fiebig, O. Schiemann, J. K. Barton, and A. H. Zewail, P. Natl.Acad. Sci. USA bf 97, 14052 (2000).

[3] B. Giese and M. Spichty, ChemPhysChem 1, 195 (2000).

I-6

INVITED Bernd Giese

notes:

I-6 (notes)

Frank Großmann

Elastic and inelasticelectron transport in nanosystems

Frank Großmann, Rafael Gutierrez, and Rudiger Schmidt

Institut fur Theoretische Physik, TU Dresden, Germanyfrank@physik.tu-dresden.de

The talk will focus on two topics: Firstly, we concentrate on the description of elasticelectron transport using the Landauer approach. The implementation of the Green’sfunction formalism in a form inspired by density functional theoretical LCAO calcula-tions is reviewed. An application to conductance calculations for sodium molecular wiresand several isomeric forms of sodium clusters of up to 11 atoms is given. Secondly, awavepacket formulation of scattering theory is employed to investigate inelastic transportusing a two degree of freedom model Hamiltonian. With this model the influence on theelectronic transmission of the coupling of the electron to a vibrational mode of the nuclearbackbone can be studied.

I-7

INVITED Frank Großmann

notes:

I-7 (notes)

Peter Hanggi

Nonlinear electron current througha short molecular wire

Elmar G. Petrov and Peter Hanggi

Institut fur Physik, Universitat Augsburg, Germanyhanggi@physik.uni-augsburg.de

The voltage and the temperature behavior of inelastic inter-electrode current mediated bya short molecular wire is analyzed within a nonlinear kinetic approach that accounts forstrong Coulomb repulsion between transferring electrons. When the coupling to the heatbath occurs via high–frequency vibration modes we predict a generally nonlinear current–voltage characteristics; i.e. an Ohmic behavior at small voltage, rising towards saturationand being followed by an abrupt decrease at large voltage. Moreover, a bell–shapedcurrent response vs. temperature occurs within an intermediate temperature regime.

I-8

INVITED Peter Hanggi

notes:

I-8 (notes)

Elisa Molinari

Electronic structure and transportin guanosine nanoaggregates

Elisa Molinari

Istituto Nazionale per la Fisica della Materia (INFM) andDipartimento di Fisica, Universita di Modena e Reggio Emilia, Italy

molinari@unimo.it

Guanosine (G) aggregates are among the simplest structures constituted by DNA basepairs that are well characterized experimentally, and were recently used in the fabricationof novel biomolecular nanodevices. Understanding their electronic and transport proper-ties is especially interesting also in view of the role played by guanine, the base with thelowest ionization potential, in charge transport and damage in DNA.We present ab-initio calculations of the stability and the electronic structure of stackeddimers and ribbons with different geometries. We discuss the implications of π–π stackingand band dispersion in determining Bloch-type band conductance, as well as the role ofmacroscopic dipoles that can build up in real nanostructures. Our conclusions allow toexplain recent experimental data on G aggregates and may shine light on the currentdebate on conduction properties of DNA.

Work performed in collaboration with Rosa Di Felice and Arrigo Calzolari (INFM andPhysics Dept, University of Modena, Italy) and Anna Garbesi (CNR ISOF, Bologna,Italy).

I-9

INVITED Elisa Molinari

notes:

I-9 (notes)

Abraham Nitzan

Inelastic effects in electron transmission throughmolecular junctions

A. Nitzan, M. Galperin, D. Segal

School of Chemistry, Tel Aviv University, Israelnitzan@post.tau.ac.il

In this talk I will discuss several aspects of electron transmission through molecular junc-tions. (a) The mechanism of electron tunneling through a narrow water barrier betweentwo Pt(100) metal surfaces was studied by numerical simulations [1]. Assuming that thewater configuration is static on the time scale of the electron motion, the tunneling proba-bility show distinct resonance structures below the vacuum barrier. These resonances areshown to be associated with molecular cavities in which the electron is trapped betweenrepulsive oxygen cores. The lifetimes of these resonances are found to be of the order10 fs or less. (b) Relaxing the assumption of static water we then calculate the effectof inelastic interaction on electron transmission through water [2]. (c) General modelsfor dephasing, inelastic effects and heat dissipation associated with molecular conductionprocesses are analyzed [3,4].

[1] U. Peskin, A. Edlund, I. Bar-On , M. Galperin, and A. Nitzan, “Transient resonancestructures in electron tunneling through water”, J. Chem. Phys. 111, 7558 (1999).

[2] M. Galperin and A. Nitzan, “Inelastic electron tunneling through water”, to be pub-lished.

[3] D. Segal, A. Nitzan, W. B. Davis, M. R. Wasielewski, and M. A. Ratner, “Electrontransfer rates in bridged molecular systems II: a steady state analysis of coherenttunneling and thermal transitions”, J. Phys. Chem. B 104, 3817-3829 (2000).

[4] D. Segal and A. Nitzan, “Steady state quantum mechanics of thermally relaxing sys-tems”, to be published.

I-10

INVITED Abraham Nitzan

notes:

I-10 (notes)

Danny Porath

Towards DNA nanoelectronics?

Danny Porath1,2, Alexey Bezryadin3, Simon de Vries2, Li Zhu1,and Cees Dekker2

1 Physics Department and Nanocenter, Tel Aviv University, Israel2 Dpt of Applied Physics and DIMES, Delft University of Technology, The Netherlands

3 Physics Department, Harvard University, USAporath@star.tau.ac.il

DNA is one of the most attractive candidates for future molecular electronics due to theextremely high density of its components, its accurate synthesis and its double-strandrecognition properties. Knowledge about the conduction properties of the DNA is crucialfor the development of nanoscale DNA–based electronics. Recently, others and we haveshown by direct electrical transport measurements that some DNA sequences can indeedsupport electrical current. It is not yet clear however, what is the electrical transportmechanism for charge carriers through DNA, what are the limits of the ability of DNAto support current and how sensitive is the electrical transport to optical excitations.The possibility that alternative DNA–based derivatives can transport current in a moreefficient manner was not studied yet by direct electrical measurements as well. In thistalk I will review our transport experiments as well as our current projects and plans foraddressing the above questions towards the development of DNA–based nanoelectronics.

[1] D. Porath, A. Bezryadin, S. de Vries, and C. Dekker, “Direct measurements of elec-trical transport through DNA molecules”, Nature 403, 635 (2000).

I-11

INVITED Danny Porath

notes:

I-11 (notes)

Herbert Scholler

Analogies between molecular electronics andquantum dots

H. Schoeller

Institut fur Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Germanyschoeller@int.fzk.de

Transport through SET devices consisting of molecular systems or quantum dots is dom-inated by the interplay of charging energy and energy quantization. We argue that mean-field like approaches can not cover the Coulomb-blockade physics which is characteristicfor a molecule being weakly coupled to electronic reservoirs via covalent bonds. For oneor two relevant molecular orbitals we analyse the transport current. We show that specialspatial dependencies of the electronic density can lead to negative differential conduc-tance [1]. For a C60 cluster we combine nanoelectronic with nanomechanical degrees offreedom and find good agreement with recent experiments [2]. Furthermore we apply anAharonov-Bohm flux and analyse interference effects and Kondo physics for low temper-atures in the strong tunneling regime [3].

[1] H. Hettler and H. Schoeller, http://arXiv.org/abs/cond-mat/0011047.

[2] D. Boese and H. Schoeller, http://arXiv.org/abs/cond-mat/0012140.

[3] D. Boese, W. Hofstetter, and H. Schoeller, http://arXiv.org/abs/cond-mat/0010250.

I-12

INVITED Herbert Scholler

notes:

I-12 (notes)

Jose M. Soler

Electronic properties of DNA from first principles

Emilio Artacho1, Pablo Ordejon2, and Jose M. Soler1

1Dep. de Fısica de la Materia Condensada and Inst. Nicolas Cabrera,Universidad Autonoma de Madrid, Spain

2Institut de Ciencia de Materials de Barcelona (CSIC),Campus de la Universidad Autonoma de Barcelona, Spain

jose.soler@uam.es

Despite much effort in the biochemical and nanoscience communities, the conductivity ofDNA remains a widely open question. Experimentally, a huge range of different results hasbeen obtained, possibly due to the complexity of the system and to the uncertainties of theexperimental setups. Theoretically, several mechanisms have been suggested, from ballis-tic band-like conduction to thermal polaronic diffusion. We are approaching the problemfrom first principles, using recent developments in linear-scaling density-functional simu-lations. We have started with the simplest system: dry acidic A-DNA with all guanines inone strand and all cytosines in the other. The infinite double helix was simulated using arepeated unit cell with eleven base pairs, 715 atoms. After 800 geometry-relaxation steps,using the linear-scaling method, a single conventional diagonalization was performed toobtain the electron eigenstates. We find a very narrow HOMO band localized in the gua-nines, a wider LUMO band in the cytosines, and a wide band gap in between. In principle,band-like semiconducting behavior could be expected from this structure, if carriers wereavailable. However, by introducing structural noise, either by changing the sequence orthrough soft vibrational modes, we find energy shifts considerably larger than the bandwidths, leading to strong localization of the electron states, consistent with Anderson’smodel. The implications of these results on on electronic transport will be discussed.Work supported by the Fundacion Ramon Areces.

I-13

INVITED Jose M. Soler

notes:

I-13 (notes)

Andrew Turberfield

Self-Assembly and a molecular machine made fromDNA

A. J. Turberfield, B. Yurke and A. P. Mills, Jr.

Department of Physics, University of Oxford, UKa.turberfield@physics.ox.ac.uk

Molecular recognition leading to Watson-Crick hybridization between complementaryDNA oligonucleotides is the basis of DNA computation [1], of self-assembly schemes thatuse DNA as ‘addressable glue’ [2] and of DNA nanostructure fabrication [3]. We reportthe construction of a new class of active nanostructure: a machine in which DNA is usednot only as a structural material but also as a fuel [4]. The machine, which has the formof a pair of tweezers, consists of two DNA duplexes linked by a flexible hinge of single-stranded DNA. It may be repeatedly closed and opened by sequential addition of ‘fuel’ and‘removal’ strands of DNA; operation of the machine alters the separation of dye moleculeson the ends of the tweezer arms on a nanometre length scale. We also demonstrate kineticcontrol of DNA hybridization: 1) hybridization is topologically inhibited by formation ofa loop complex with a protective strand; 2) a DNA catalyst promotes hybridization bypartially displacing the protective strand and opening the loop. These results suggestthe possibility of using cooperative interactions to control non-equilibrium self-assembly,a generalization of conventional equilibrium self-assembly strategies with important im-plications for the design of DNA computers and for the fabrication of nanometre-scaledevices.

[1] L. M. Adleman, Science 266, 1021 (1994).

[2] C. A. Mirkin, R. L. Letsinger, R. C. Mucic, and J. J. Storhoff, Nature 382, 607 (1996).

[3] J. Chen and N. C. Seeman, Nature 350, 631-633 (1991).

[4] B. Yurke, A. J. Turberfield, A. P. Mills, Jr., F. C. Simmel, and J. L .Neumann, Nature406, 605 (2000).

I-14

INVITED Andrew Turberfield

notes:

I-14 (notes)

Heiko Weber

Experimental investigation of electronic transportthrough a single organic molecule

H. B. Weber1, J. Reichert1, R. Ochs1, D. Beckmann1, H. v. Lohneysen2,and M. Mayor1

1Institut fur Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Germany2Institut fur Festkorperphysik, Forschungszentrum Karlsruhe, and

Physikalisches Institut, Universitat Karlsruhe, Germanyheiko.weber@int.fzk.de

We have measured electronic transport at room temperature through single conjugatedorganic molecules connected via thiol groups to gold electrodes using the break junctiontechnique. Nonlinear current-voltage characteristics (I–V s) were recorded. Typical over-all conductance of the metal-molecule-metal junction scatters within a range of only 50%.Small deviations from measurement to measurement display different microscopic realiza-tions of the contacts. We have chosen two similar linear molecules which differ essentiallyby their spatial symmetry. The I–V s we observe for both molcules reflect clearly thesymmetry of the molecule and give evidence of transport through a single molecule.

I-15

INVITED Heiko Weber

notes:

I-15 (notes)

Sophia Yaliraki

Structure and transport inbinary self-assembled monolayers

Sophia N. Yaliraki

Department of Chemistry, Imperial College, UKs.yaliraki@ic.ac.uk

Molecular electronic device elements such as wires, switches, rectifiers have recentlybeen demonstrated. Whether achieved by nanofabrication techniques or chemical self-assembly, these systems involve an ensemble of molecules incorporated between metalelectrodes. Despite the impressive experimental demonstrations, variations in structuresare inevitable. Furthermore, organizing and interfacing elements in controlled ways re-mains a substantial challenge.We apply our previously developed theory of conductance of molecular junctions to ag-gregates and show how transport depends on the number and conformation of moleculespresent in the junction. We identify the parameters that control structure and the impli-cations to electronic transport and device performance.

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INVITED Sophia Yaliraki

notes:

I-16 (notes)

CONTRIBUTED ABSTRACTS(in alphabetic order of the presenting author)

CONTRIBUTED Christoph Bruder

Anderson-type modelfor a molecule adsorbed on a metal surface

Mahn-Soo Choi and C. Bruder

Departement Physik und Astronomie, Universitat Basel, Switzerland

We investigate a modified Anderson model to study the local density of states (LDOS) ofa molecular wire adsorbed on a metal. Using a self-consistent mean-field type approach wefind an exponential decay of the LDOS along the molecule. A repulsive on-site interactionon the molecule suppresses the tunneling and decreases the characteristic decay length.

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CONTRIBUTED Lucio Colombi Ciacchi

Mechanism for the nucleation ofplatinum cluster on biopolymers

Lucio Colombi Ciacchi, Ralf Seidel, Michael Mertig, and Wolfgang Pompe

Institut fur Werkstoffwissenschaft, Technische Universitat Dresden, Germany

The mechanism for the nucleation of platinum clusters on biomolecules (DNA and pro-teins) is studied by means of first-principles molecular dynamics simulations, spectroscopy,atomic force microscopy and transmission electron microscopy. We identify a “catalytic”role of the biotemplate in the initial stage of cluster nucleation after reduction of platinumsalt in solution. If an amount of metal complexes is allowed to bind to the biopolymerbefore starting the reduction, the first formed Pt–Pt bonds are stabilized by the presenceof nucleophilic ligands. This leads to a preferential growth of clusters on the biotemplate,which is the base for the production of bio-anorganic structures like cluster chains andarrays.

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CONTRIBUTED Gianaurelio Cuniberti

Fingerprints of mesoscopic leadson the conductance through a molecular wire

G. Cuniberti, G. Fagas, and K. Richter

Max-Planck-Institut fur Physik komplexer Systeme, Dresden, Germany

The influence of contacts on linear transport through a molecular wire attached to meso-scopic tubule leads is studied. It is shown that low dimensional leads, such as carbonnanotubes in contrast with more bulky electrodes, strongly affect transport properties.By focusing on the specificity of the lead–wire contact, we show that the geometry ofthis hybrid system supports a mechanism of channel selection and a sum rule, which isa distinctive hallmark of the mesoscopic nature of the electrodes. In particular, depend-ing on the quality and geometry of the contacts between the molecule and the tubularreservoirs, linear transport can be tuned between an effective Newns spectral behaviorand a more structured one. The latter strongly depends on the topology of the leads.We also provide analytical evidence for an anomalous behavior of the conductance as afunction of the contact strength and provide an analytical form for the conductance of anhomogeneous molecular wire generalized to the case of a nonvanishing real self energies,typical when considering nanotube leads.

[1] G. Cuniberti, G. Fagas, and K. Richter, to appear in “Nanotubes and Nanostructures”(2001).

[2] G. Cuniberti, G. Fagas, and K. Richter, Acta Phys. Pol. 32, 437 (2001).

[3] G. Fagas, G. Cuniberti, and K. Richter, Phys. Rev. B 63, 045416 (2001).

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CONTRIBUTED Francesca De Rienzo

Theoretical descriptors and QSPR analysis ofplastocyanin mutants

F. De Rienzo and M. C. Menziani.

Dipartimento di Chimica, Universita di Modena e Reggio Emilia, Italy

The theoretical Quantitative Structure Property Relationship (QSPR) methodology isincreasingly being applied in the development and design of biologically active moleculesof small dimensions [1] such as drugs or insecticides, where as applications of QSPRto peptides and proteins have been little developed. Current studies in this field relyessentially on amino acid side chain scores derived by the application of the principalcomponent analysis (PCA) to descriptor matrices of different nature, such as empiricalscales, 3D descriptors, interaction property descriptors, etc. [2] Sound statistical modelswith good predictive ability have been reported in the literature, but the approach suffersof two severe drawbacks: the descriptors are computed on isolated amino acids or on verysimple model systems and the physical interpretation of the correlations obtained is oftendifficult. In this work, the performance of theoretical descriptors, originally generatedto explain properties of small molecules, in rationalising the experimentally observedvariations of functional properties of a series of plastocyanin mutants was tested. Inparticular, surface descriptors computed on the 3D structure of the mutants proved to beuseful to pinpoint the causes that determine variations in molecular properties such asredox potential and electron transfer kinetic constants.

[1] Karelson et al., Chemical Reviews 96, 1027-1043 (1996).

[2] Sandberg et al., Journal of Medicinal Chemistry 41, 2481-2491 (1998).

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CONTRIBUTED Giorgos Fagas

Electron transport across molecular wires connectedto nanotube electrodes

G. Fagas, G. Cuniberti, and K. Richter

Max-Planck-Institute fur Physik komplexer Systeme, Dresden, Germany

We investigate interfacial contact effects on the electric conductance of a molecular bridgebetween (carbon) nanotube leads, which serve as an example of mesoscopic electrodes.This problem has been tackled both numerically and analytically within the Landauerapproach which relates the conductance to a scattering problem. Here, we focus on thenumerical results obtained by employing a recursive Green function technique to calculatethe quantum-mechanical scattering matrix.Owing to low-dimensionality, electron transport is very sensitive to the strength andgeometry of interfacial bonds, and also to the profile of wave functions transverse to thetransport direction. Molecular contact between a single interfacial atom and electrodesgives rise to complex conductance dependence on the electron energy exhibiting spectralfeatures of both the molecule and electrodes. These are attributed to the electronicstructure of the molecular wire and to the local density of states of the leads, respectively.Multiple bonding provides a mechanism for the control of the conductance. Variationof the coupling strength between a molecular complex and the leads gives rise to a non-monotonic behaviour of molecular resonances in the conductance spectrum. Work inprogress is based upon a quantum chemical approach utilising density functional theoryand addresses transport across fullerene molecules considered as a nano-bridge.

[1] G. Fagas, G. Cuniberti, and K. Richter, Phys. Rev. B 63, 0454161 (2001).

[2] G. Cuniberti, G. Fagas, and K. Richter, Acta Phys. Pol. B 32, 437 (2001).

[3] G. Fagas, G. Cuniberti, and K. Richter, to be published in Proceedings of the VInternational Conference on ‘Molecular Electronics’ (2001).

[4] G. Cuniberti, G. Fagas, and K. Richter, to be published in ‘Nanotubes and Nanos-tructures’ (2001).

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CONTRIBUTED Dmytro Fedorets

Quantum theory of shuttle instability

D. Fedorets, L. Y. Gorelik, R. I.Shekhter, M. Jonson

We have considered resonant tunneling through a double tunnel junction where the cen-tral island is mechanically connected to the electrodes by elastic deformable links. It wasassumed that only one energy level is available in the dot. The effects of the couplingbetween mechanical vibrations of the dot and resonant tunneling of electrons through thelevel in the dot have been studied by means the Keldysh nonequilibrium Green functionstechnique. It was shown that at voltages exceeding certain critical value dynamical insta-bility occurs and mechnical vibrations of the dot develops. The origin of the instabilityis a synchronization between time dependent quantum fluctuations of the charge on thedot and its mechanical oscillations.

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CONTRIBUTED Rafael Gutierrez

Electronic transport in small cluster

Rafael Gutierrez, Frank Großmann, and Rudiger Schmidt

Institute for Theoretical Physics, Technical University Dresden, Germany

We present first calculations on electric transport properties of small sodium clustersNaN (N ≤9) based on the Landauer formalism combined with an approximate density-functional approach. For a given cluster size N , the resistance depends sensitively on thecluster geometry (isomers). As a function of cluster size, an even-odd oscillation of theminimal resistance is found.

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CONTRIBUTED Walter Hofstetter

Interference and interaction effects inmulti–level quantum dots

Daniel Boese1,2, Walter Hofstetter3, and Herbert Schoeller2,1

1 Institut fur Theoretische Festkorperphysik, Universitat Karlsruhe, Germany2 Institut fur Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Germany

3 Theoretische Physik III, Elektronische Korrelationen und Magnetismus,Institut fur Physik, Universitat Augsburg, Germany

We study spectral and transport properties of a spinless interacting quantum dot consist-ing of two levels coupled to metallic reservoirs. Renormalization Group methods (includ-ing Wilson’s Numerical RG) are used to solve the corresponding many–body problem.For strong Coulomb repulsion U and an applied Aharonov-Bohm phase φ, we find a largedirect tunnel splitting |∆| ∼ (Γ/π) cos2(φ/2) ln(U/ωc) between the levels of the order ofthe level broadening Γ. As a consequence we discover a many-body resonance in the spec-tral density which can be measured via the absorption power. Furthermore, we show thatthe system can be tuned into an effective Kondo model by changing the Aharonov-Bohmphase to φ = π.

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CONTRIBUTED Andreas Isacsson

Nanomechanically mediated Josephson couplingbetween remote superconductors

L. Y. Gorelik, A. Isacsson, Y. M. Galperin, R. I. Shekhter, and M. Jonson

We show that a movable nano scale superconducting grain can mediate Josephson couplingbetween two remotely separated superconducting leads. Cooper-pair exchange betweenthe leads is established when the grain executes periodic motion contacting the leads se-quentially. By ensuring that a single Cooper-pair-box situation occurs at each encounterwith a lead the state of the grain will be a coherent hybrid of two states with zero andone extra Cooper pair respectively. As a result, phase coherence between remote super-conductors can be established and maintained and a non dissipative Josephson current,which can be nonzero even if the phase difference between the leads is zero, is predictedto appear.

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CONTRIBUTED Sihem Jaziri

Electronic coupling of vertically coupled quantumdots: effect of time-dependent electric field.

S. Jaziri1, E. Ben Salem, W. Ben Chouikha

Laboratoire de Physique de la Matiere Condensee,Faculte des Sciences de Tunis, Tunisie

1Departement de Physique, Faculte des Sciences de Bizerte, Tunisie

We study the entanglement of two electrons confined in two vertically tunnel coupled-quantum dots subjected to time dependent electric field. Entanglement is at the sourceof a number of pure quantum phenomena. Entanglement between two or more electronswas generally viewed as a consequence of the fact that the electrons involved did originatefrom the same source or at least were interacting at some earlier time. We investigatethe dynamical response of the two interacting electrons in double quantum dots withan arbitrarily electric field. We find for certain constant electric field ranges and at acertain time the two electrons are localised in the one of the dot. In the presence of anoscillatory electric field and for certain frequency ranges a sinusodal perturbation acts likean entanglement of the two electrons in either dot with equal probability.

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CONTRIBUTED Ivan Kondov

Numerical studies of ultrafast electron transferin betaine-30

I. Kondov, U. Kleinekathofer, and M. Schreiber

Institut fur Physik, Technische Universitat, D-09107 Chemnitz, Germany

Charge transfer dynamics in a model system with two charge localization states is in-vestigated applying the Redfield theory (without rotating wave approximation). Tworeaction coordinates are taken into account. The diabatic potential energy surface (PES)of the system is modeled as coupled harmonic potentials and the bath is considered tobe of Ohmic type with exponential cut-off. In this system the electron transfer processis a spontaneous transition from an electronically excited state to the ground state withcharge separation. The parameters are chosen such as to describe betaine-30 in solution.Earlier calculations for this system involved only one reaction coordinate [1]. As a firstevidence of the advantage of this approach the rate of the reaction in different media wascalculated.Recently it has been established that the exact solution of the Redfield equations requireseigenstate representation for the reduced density matrix and the Redfield tensor especiallyfor strong coupling between the diabatic electronic states or for specific PES configurations[2]. Within this approach the influence of the intercenter coupling on the system-bathinteraction is properly taken into account.

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CONTRIBUTED Paul Low

Organometallic molecular wires and switches

Tom Snaith, Olivia Koentjoro, Horst Puschmann, Judith A. K. Howard,Roger Rousseau and Paul J. Low*

Organometallic complexes offer well-defined redox properties and spectroscopic handles,which when combined with the structural and electronic versatility inherent in thesesystems make them particularly useful building blocks for the construction of molecularscale electronic devices.Metal-ligand pi-conjugation in several organometallic systems containing highly unsatu-rated polyynyl, polyyndiyl and aryl ligands have been examined using a combination ofspectroscopic, electrochemical, structural and computational methods. The most signif-icant transmission of electronic effects between the metal and ligand pi systems occursby mixing of filled orbitals from each fragment. Spectroelectrochemical techniques havebeen used to probe the electronic structure of mixed-valence complexes and identify strongmetal-metal coupling through the diyndiyl ligand.Work currently in progress aiming to prepare materials with directional or switchablemetal interactions will be described.

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CONTRIBUTED Lyuba Malysheva

Effects of molecule-to-lead connections in the systemmetal-molecule-metal

L. I. Malysheva1 and A. I. Onipko2

1Bogolyubov Institute for theoretical physics, Kiev, 03143, Ukraine2 IFM, Linkoping University, S-581 83 Linkoping, Sweden

Experiments in the field of molecular electronics are accompanied by an increasing the-oretical effort aimed at the understanding of the relationship between the nature ofmolecule-to-metal electron coupling and the observed current-voltage (I–V ) character-istics. The zero-temperature zero-bias ballistic conductance, which is 2e2/h times thetransmission coefficient T (E) at the Fermi energy, can be expressed in the form T (E) =4∆1(E)∆N(E)|G1,N |2, where ∆1(N) is the spectral density of the left (right) lead in thesystem metal-molecule-metal, and the Green function matrix element G1,N(E) refers tothe molecule binding sites 1 and N . The molecule-metal interaction is included exactly inG1,N (E) making it dependent on ∆1(N)(E), i.e., on a combination of the Green functionsassociated with the semi-infinite leads and referred to the metal atoms involved in themetal-molecule interaction.Since the given equation or its analogies have been proven useful as a tool for studyingprincipal factors that rule the molecular conductance, finding the energy dependence of∆1(N)(E) and G1,N(E) by analytical methods is especially desirable. In this work, wepresent I–V characteristics of likely models of molecule-to-substrate/tip contacts. These(schematically shown in Fig. 1.) are discussed to illustrate, how, on one hand, the localdensity of states on the molecular tip-facing atom and, on the other hand, the local densityof states on the tip apex atom may affect the apparent I–V relation.

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CONTRIBUTED Volkhard May

Density matrix theory of electron transfer inmolecular complexes: from slow nonadiabatic

reactions to the femtosecond laser pulse control ofultrafast reactions

V. Maya, T. Mancala, Ye. V. Shevchenkob, Ya. R. Zelinskjjb,and E. G. Petrovb

The contribution reviews recent studies on electron transfer (ET) reactions in donor ac-ceptor systems interconnected by bridging molecular structures. Based on a model of theET system which includes active electron–vibrational states as well as the coupling toa thermal reservoir of passive vibrational coordinates the approach accounts for vibra-tional relaxation in the course of the ET and enables one to study different regimes ofET reactions [1,2]. For the case of ET processes being slow compared to the relaxationwithin the sites of the donor bridge acceptor system a treatment of the respective densitymatrix equations is presented which simultaneously accounts for the superexchange aswell as the sequential type of ET and is valid for any number of bridge molecules [3]. Thepossible control by high–frequency electric fields is indicated [4]. If the ET proceeds on atime–scale comparable to intra–site vibrational relaxation femtosecond laser pulse controlcan be carried out. In combining the density matrix approach with the theory of optimalcontrol the guided motion of the electron along the ET chain is demonstrated [5].

[1] E. G. Petrov, Physics of Charge Transfer in Biosystems (Naukowa Dumka, Kiev, 1984,in Russian).

[2] V. May and O. Kuhn, Charge and Energy Transfer Dynamics in Molecular Systems,(Wiley-VCH, Berlin, 1999).

[3] E. G. Petrov, Ye. V. Shevchenko, V. I. Teslenko, and V. May, J. Chem. Phys. (sub-mitted)

[4] I. A. Goychuk, E. G. Petrov, and V. May, Chem. Phys. Lett. 253, 428 (1996).

[5] T. Mancal and V. May, Euro. Phys. J. D (in press).

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CONTRIBUTED Jose Luis Mozos

New method for first principles modelling ofelectron transport trough nanoelectronic devices.

Jose Luis Mozos, Pablo Ordejon,

Institut de Ciencia de Materials de Barcelona CSICCampus de la UAB, Spain

Mads Brandbyge, Kurt Stokbro, and Jeremy Taylor

Mikroelektronik Centret, Technical University of Denmark, Denmark

We present a theoretical method of modelling electron transport through nanostructuresunder nonequilibrium conditions. The method is a combination of an equilibrium LCAOcode (SIESTA) [1] with the nonequilibrium Green’s function formalism [2]. Fully self-consistency is obtained for open systems under a potential bias on the same grounds asthe equilibrium calculation. In addition the detailed atomic structure of both the contactregion and leads of the nanostructures is fully taken into account.We demonstrate our method with calculations of ballistic electron transport through ofdiverse contacts sandwiched between both nanowires and carbon nanotubes.

[1] D. Sanchez-Portal, P. Ordejon, E. Artacho and J. M. Soler, Int. J. Quantum Chem.65, 453 (1997).

[2] M. Brandbyge, N. Kobayashi, and M. Tsukada, Phys. Rev. B 60, 17064 (1999).

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CONTRIBUTED Tomas Nord

Electromechanics of charge shuttling in dissipativenanostructures

T. Nord, L. Y. Gorelik, R. I. Shekhter, M. Jonson

We investigate the current-voltage (I–V ) characteristics of a single-electron transistorwhere mechanical displacement, subject to dissipation, of a small metallic grain is possible.The system is studied both using Monte-Carlo simulations and an analytical approach. Weshow that electromechanical coupling results in a highly nonlinear I–V -curve. Above theCoulomb blockade threshold two distinct regimes of charge transfer occur: At low voltage,the grain moves slowly on the scale of charge relaxation occuring due to tunneling, andelectron tunneling is the dominating charge transfer mechanism (tunneling regime). Athigher voltages an abrupt transition to a new regime appears, where the grain movesquickly on the scale of charge relaxation. In this shuttle regime the charge transfer occurspartially due to the charge being moved by the grain and partially due to tunneling.

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CONTRIBUTED Monica Pickholz

Polarons and solitons in trans-polyacetylene dimers:an ab initio MP2 study.

Monica Pickholz, Anna Pohl, and Sven Stafstrom

Department of Physics and Measurement Technology, Linkoping University, Sweden

Charged polyene dimers were investigated using MP2 theory. We found stable molecularcomplexes formed by two singly charged polyenes with even number of carbons. Therelative stability of these dimers was compared with dimers of a neutral molecule and onedoubly charged molecule. The energy difference per carbon (favourable to the two singlycharged polyenes) decrease with increasing length of the polyene. The dimer with oneneutral and one doubly charged molecule pair became the most stable when conter-ionsare taken into account explicitly. Charged solitons and polarons dimers were studied forlonger polyenes (C31H33 and C30H32, respectively). The results show that, both polaronsand solitons repell each other. This effect is, however, stronger in the soliton pair case.

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CONTRIBUTED Jan Richter

Conductivity of metallic nanowires assembled onDNA

J. Richter1, H. Vinzelberg2, I. Monch2, H. K. Schackert3, M. Mertig1,and W. Pompe1

1 Institut fur Werkstoffwissenschaft, Technische Universitat Dresden, Germany2 Institut fur Festkorper- und Werkstofforschung, Technische Universitat Dresden,

Germany3 Abteilung Chirurgische Forschung, Universitatsklinikum der Technischen Universitat

Dresden, Germany

We present measurements of the electrical conductivity of 50-100 nm thick palladiumnanowires assembled on a DNA-templat. The DNA molecules have been positionedbetween macroscopic Au electrodes and are metallized afterwards. The investigatednanowires exhibit ohmic transport behavior. The maximum specific conductivity is onlyone order of magnitude below that of bulk palladium. Some nanowires show non-metalliclow temperature behavior revealed by an increase of resistance with decreasing tempera-ture for temperatures below 30 K. The slope of the decrease follows a logarithmic law andcan be very well described by a two-dimensional electron system in a disordered metal.Thus, the approach of biotemplating proofed to be capable for the formation of metallicnanosystems with quantum behavior.

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CONTRIBUTED Elisa Molinari

Phase diagram of vertically coupled quantum dots:an exact diagonalization study

M. Rontani, F. Manghi, G. Goldoni, and E. Molinari

INFM and Dipartimento di Fisica, Universita di Modena e Reggio Emilia, Italy

Coupled QDs constitute ‘artificial molecules’ (AMs) [1] where the interdot coupling canbe tuned through external parameters, far out of the regimes known in ‘natural’ systemswhere the ground-state interatomic distance is dictated by the nature of bonding. Dueto the interplay between single-particle effective confining potential, hopping, Coulombinteraction, and magnetic fieldB, AMs display a rich phase diagram of different correlatedelectronic states. The ground (excited) states can be probed my means of (non-) linearSingle-Electron Transport Spectroscopy: the key quantity is the addition energy, i.e. theenergy required to add one electron to the dot. Until now, relatively few measurements ofaddition spectra in systems of coupled vertical QDs have been reported [1]. In this workwe solve exactly the full Hamiltonian for a realistic device up to 6 electrons. The energyspectrum we find presents a rich variety of correlated ground states as we apply an externalmagnetic field B and vary the inter-dot distance d. We study exactly all different couplingregimes, from the limit where the inter-dot kinetic energy term dominates over intra-dotCoulomb interaction to the opposite limit where the former term is negligible. For agiven number of electrons, we find that when d is large the system behaves as two isolatedQDs, and the inter-dot interaction is purely electrostatic as expected. With decreasing d,phases of non-trivial spin polarization and magnetization are found in addition to statesunderstandable in terms of a single-particle picture combined with Hund’s rule. Theseunexpected phases show a peculiar behavior in the addition spectrum vs B. If d is stillreduced one regains the transition to the single coherent dot. When B is switched on,we study how the ‘maximum density droplet’ region (analogous to the ν = 1 state ofthe bulk Integer Quantum Hall Effect) changes as d varies. At B = 11 T we find clearsignatures of electronic localization, corresponding to different ‘geometric’ configurationsas d is varied. The above findings are expected to be experimentally observable: First,the calculated magnetic-field dependent addition spectra present clear signatures of thephase transitions described above. Secondly, the excitation spectra can be also comparedwith those obtained by non-linear transport measurements [2]. Lastly, the changes in themagnetization induced by the addition of one electron are expected to follow a differentpattern in each phase. These predictions seem to be confirmed by some preliminaryexperimental data [3].

[1] D.G. Austing et al., Jpn. J. Appl. Phys. 36, 1667 (1997); Physica B 206, 249-251(1998).

[2] L.P. Kouwenhoven et al., Science 278, 1788 (1997).

[3] D.G. Austing et al., unpublished.

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CONTRIBUTED Reinhard Scholz

Electronic transport and defect properties ofPTCDA-modified Schottky contacts on S-passivated

GaAs(100)

S. Park, I. Thurzo, Th. Lindner, T. U. Kampen, R. Scholz, andD. R. T. Zahn

Institut fuer Physik, Technische Universitaet Chemnitz, Germany

With increasing interest in organic semiconductors for electronic and optoelectronic de-vices, a new potential application of these organic semiconductors was reported, namely amodification of conventional Schottky contacts using a thin interlayer of organic semicon-ductors [1]. Using a prototype organic semiconductor, perylene-3,4,9,10-tetracarboxylicdianhydride (PTCDA) as a modification and Ag as an unreactive top electrode, the in-fluence of GaAs(100) surface preparation and PTCDA film thickness on the electronictransport properties was investigated using in situ current-voltage (IV) measurements.The sulfur passivation of GaAs(100) creates an additional surface dipole and thereforea decrease of the barrier height of Ag/n-GaAs(100) Schottky contacts. Furthermore, adependence on the PTCDA layer thickness is observed, resulting in a barrier height be-tween 0.54 0.73 eV. Interestingly, the CV characteristics does not vary upon introducingan organic interlayer, indicating the overall capacitance stems from the depletion layerwithin the GaAs substrates without further modification by the PTCDA layer. Therefore,the change in the effective barrier height is attributed to the transport properties of theorganic layer.A comparison of charge transport properties of the organic/inorganic Schottky diodes,as monitored respectively in situ (UHV) and after exposure to air, revealed a stronginteraction of either water or oxygen with PTCDA thin films. The resulting defect ordoping levels lead to a significant decrease of the electrical conductivity of the organicmaterial. Starting from the notion of a reduced mobility of charge carriers in air-exposedPTCDA, charge deep-level transient spectroscopy (Q-DLTS) experiments were started.In in situ Q-DLTS spectra of the diodes, a discrete bulk level of GaAs (ET2) alongwith a continuous energy distribution of interface states dominated, whereas three air-induced trapping levels at 0.03, 0.18 and 0.75 eV, respectively, could be detected. Thetwo relatively shallow levels were ascribed to defects in PTCDA, while the 0.75 eV level(ELO) was already detected earlier in oxygen plasma treated n-type GaAs. Consequently,there is evidence for trap-limited charge transport (mobility) in air-exposed PTCDA thinfilms.

[1] A. Vilan, A. Shanzer, and D. Cahen, Nature 404, 166 (2000).

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CONTRIBUTED Gotthard Seifert

Electronically functionalized carbon nanotubes

G. Seifert, Th. Koehler and Th. Frauenheim

Theoretical investigations about the changes of the properties of single wall carbon nan-otubes (SWNTs) by fluorination are reported. It is shown that a side-wall functionaliza-tion of SWNTs may lead to tubes with a wide variety of electronic properties, rangingfrom insulating, over semiconducting to a metallic-like behaviour. Therefore a chemicalderivatization of SWNTs may open new possibilities for tailoring the electronic propertiesof nanotubes, providing nanoscale wires, capacitors and solenoids.

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CONTRIBUTED Sven Stafstrom

Electron transport in carbon basednanostructured materials

S. Stafstrom, A. Hansson, M. Hjort, A. Johansson, and M. Paulsson

Department of Physics, IFM, Linkoping Univ., Swedensst@ifm.liu.se

Quasi one-dimensional π-conjugated carbon based systems such as carbon nanotubes,conjugated polymers and π-stacks are all of interest in the context of molecular electronics.Charge transport along and between such wires include a wide range of applications:molecular wires for nano-electronics, polymer light emitting diodes, understanding of somespecific properties of base-pair stacking in DNA etc.. In this contribution we discuss thecomputational techniques used in calculations of electron transport in this kind of systems,both in the ballistic regime and in the case of electron localization induced by disorder. Inparticular we will discuss the role of intermolecular interactions in the transport process.These studies involve conductance and current distribution in multiwall carbon nanotubes,polaron and soliton hopping between polymer chains and electron localization in π-stacksand DNA.

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CONTRIBUTED Jorg Stephan

Monte-Carlo simulation of charge carrier transportin disordered molecular solids

Jorg Stephan, Ludwig Brehmer

Institut fur Physik, Physik kondensierter Materie,Universitat Potsdam, Germany

We study the effect of spatial disorder, anisotropy and sample orientation on the field-dependent mobility of charge carriers in thin organic layers using a dynamic Monte Carlosimulation. Our transfer rate is based on a polaronic model of phonon-assisted hoppingin an effective diabatic potential (Marcus-theory). We find that our simulations, in con-trast to the Gaussian Disorder Model or the Correlated Disorder Model, do not requireunphysical model parameters or correlated disorder to explain experimental data for thefield and temperature dependence of mobilities. Our simulations show, that no energeticdisorder is necessary to fit experiments; a clear transition from a 3-D diffusion and driftlimited mobility to a quasi 1-D drift limited process with increasing external fields inthe presence of spatial disorder can be observed; a well-controlled degree of disorder canunder certain conditions increase carrier mobility and simulated mobilities on a regularlattice depend strongly on the direction of the external field with respect to the lattice ina non-trivial and field-dependent manner.

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CONTRIBUTED Michael Torker

Scanning Tunneling Microscopy/Spectroscopyinvestigation of the organic molecules PTCDA and

HBC on Au(100)

M. Toerker, T. Fritz, H. Proehl, F. Sellam and K. Leo

Institut fur Angewandte Photophysik, Technische Universitat Dresden, Germany

Highly ordered organic thin films on Au(100) single crystals have been investigated byScanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS)at room temperature. The organic dye molecule perylene-tetracarboxylic-dianhydride(PTCDA) has been deposited as submonolayer coverage. I–V -spectroscopy at fixed tip-sample-separations performed alternately on PTCDA islands and on uncovered areas ofthe Au(100) surface revealed a clear chemical contrast. The normalized derivatives ofthe I–V -curves corresponding to PTCDA islands have then been compared to inversephotoelectron spectroscopy data known from literature, indicating resonant tunnelingvia the lowest unoccupied molecular orbital of PTCDA. As a second molecule, peri-hexabenzocorone (HBC) has been investigated. The Au(100) surface has been fully cov-ered by a 1..2 monolayers thick, highly ordered HBC film. The normalized derivativesof I–V -curves measured on these films show a pronounced local maximum at a voltageof about -1.4 V. By comparison with ultraviolet photoelectron spectroscopy (UPS) mea-surements of HBC on Au(111) we can show that this peak in the tunneling spectroscopyplot is due to resonant tunneling via the highest occupied molecular orbital of HBC.

C-24

CONTRIBUTED Karsten Walzer

Self-assembled monolayers of

organic “molecular wires”studied by scanning tunneling microscopy

K. Walzer, K. Stokbro, R. Lin, P. Raithby

Mikroelektronik Centret Danish Technical University, Denmark

Organic molecules posessing thiol end groups can be used to self-assemble organic mono-layers onto noble metal surfaces. Using this method, we have self-assembled electricallyconductive molecular rods of thiol-4,4’-di(ethynylphenyl)-2’-nitro-1-benzenethiolate (alsocalled “Tour-wires”) onto Au(111) surfaces. The molecules were synthesised following adescription in [1]. The molecular self-assembly is accomplished by dissolving the moleculesin tetrahydrofurane (THF), where the substrate remains for several hours. The moleculesbind with one thiol end group covalently to the substrate, while the rod itself seems tostand upright, as we show by scanning tunneling microscopy (STM). Furthermore, weinvestigate the conductance properties of these SAMs by scanning tunneling spectroscopyunder UHV conditions, using a low-temperature STM.

[1] Chen, W. Wang, M. A. Reed, A. M. Rawlett, D. W. Price, J. M. Tour, Appl. Phys.Lett. 77, 1224 (2000).

C-25

CONTRIBUTED Edward Zenkevich

Pathways and mechanisms of photoinduced electrontransfer in nanoscale self-assembled multiporphyrin

arrays

E. I. Zenkevich1, A. M. Shulga1, Ch. von Borczyskowski2

1Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus,Belarus

2Institute of Physics, University of Technology Chemnitz, Germany

Understanding the factors and mechanisms that control the energy migration (EM) and photoinduced electron transfer

(PET) is essential for the detailed analysis of primary photoevents in natural photosynthesis and for the rational design of

a wide variety of molecular photonic devices. Within last two years, using a combined covalent and noncovalent approach

we realised a simple and yet potentially versatile strategy for fabricating highly organized multimolecular tetrapyrrolic

assemblies with or without electron acceptors of various nature, which are covalently (quinone, pyromellitimide) or coordi-

natively (pentafluorinated porphyrin extra-ligand) linked to Zn-porphyrin dimer, in solutions and polymeric (PMMA) films.

Electronic excitation energy deactivation in these nanoscale arrays has been studied by ps time correlated single photon

counting technique the experimental response ∆t1/2 ≈ 30 ps) and fs pump-probe technique (∆t1/2 ≈280 fs) as a function of

the solvent polarity (toluene-acetone mixtures), temperature (77-350 K), and mutual spatial arrangement of the donor and

acceptor subunits. The main finding are the following. In the triads consisting of the Zn-octaethylporphyrin chemical dimer

(the energy and electron donor, D) and porphyrin extra-ligands (acceptors, A) the D fluorescence quenching with time

constant ranging from 1.7 ps to 10 ps is due to competing EM and PET processes at 293 K. In addition, the A fluorescence

decay time shortening (by ∼1.3-1.6 times in toluene) is observed that becomes stronger upon the solvent polarity increase

or the temperature lowering (down to 221 K). The quenching of the extra-ligand S1-state originates from the hole transfer

to the Zn-porphyrin dimer from the extra-ligand being weakened by thermal exchange of the close lying charge transfer

and extra-ligand locally excited S1-states. In the triads with the pentafluorinated porphyrin (PF) extra-ligand (A), the

exergonic PET from the Zn-octaethylporphyrin chemical dimer to A (within ∼600-700 fs at 293 K) is the main process

leading to the drastical quenching of the dimer and PF S1 states followed by the effective formation of the extra-ligand

low-lying triplet state. Because of the stabilization of the ZnP+ radical cation by pyridyl rings, this PET is not slown down

remarkably at 164 K and remains very efficient at 120-77 K in rigid glassy solvent matrices and PMMA films, mimicking the

low temperature photoinduced charge separation in reaction centers of natural photosynthetic systems. In self-organized

tetrads of the same structure containing the additional electron acceptor (quinone, Q or pyromellitimide, Pim) covalently

linked to the Zn-octaethylporphyrin chemical dimer, the strong fluorescence quenching of the dimer (τS <3 ps) is attributed

both to the singlet-singlet EM (Zn-dimer–>extra-ligand) and the sequential PET (Zn-dimer–>Q or Pim) at rDA=10.8 A

(Q) and 13.0 A (Pim). In addition, the fluorescence decay shortening by 5-10 times (more pronounced in the case of Q) is

observed for extra-ligands in the tetrads with respect to those for individual monomers. The last shortening is noticeably

not affected by the temperature increase but depends on the ligand nature: These facts are explained in terms of PET via

the superexchange mechanism where a spectator CT state of the triad [extra-ligand+-(Zn-dimer)−−A] mediates the direct

ET from the extra-ligand to a distant (R'18-21 A) acceptor (Q or Pim) resulting in an effective transfer rate. In this case

the only role of the bridge (Zn-dimer) is to provide virtual orbitals that determine the effective DA coupling.

C-26

CONTRIBUTED Edward Zenkevich

Through-space through-bond electron transfer withparticipation of S1- and T1- states in stericallyhindered mesonitrophenylporphyrins and their

chemical dimers

E. I. Zenkevich, V. N.Knyukshto, E. I.Sagun, A. M. Shulga

Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus,Belarus

Synthetic porphyrins and their dimers, covalently linked to electron acceptors by spacers of various nature and flexibilityare widely used to model some aspects of photosynthetic electron transfer events. Obviously the electronic properties ofthe spacer determine the mechanism (“through-bond” or “through-space”) and rate constants of the photoinduced electrontransfer (PET) in donor-acceptor (D-A) pair. In addition, steric interactions of the bulky spacer with connected D-Asubunits leading to conformational changes of porphyrin macrocycle may influence both the deactivation of porphyrinexcited states and PET efficiency. Here, we analyse the dynamics and mechanisms of PET in the conditions of stericinteractions of the phenyl spacer with porphyrin macrocycle for a series of mono- and di-mesophenyl octaethylporphyrins,OEP’s (free bases, Zn- and Pd-complexes, their chemical dimers), having NO2 groups in ortho-, meta or para-position ofthe mesophenyl spacer. The main results obtained at 77-300 K using laser transient absorption measurements (λex=532nm, ∆t1/2 '50 ns), fluorescence and phosphorescence data are as follows.At 293 K in degassed toluene solutions, mono- and di-mesophenyl substitution in OEP?s as well as the formation of OEPchemical dimers with the phenyl spacer lead to the strong shortening of T1- states decays (by 300-1000 times) without anyinfluence on spectral-kinetic parameters of S0- and S1- states. The observed effects are connected with torsional librations ofthe phenyl ring around a single C-C bond in sterically encumbered porphyrins of OEP type leading to non-planar dynamicdistorted conformations realised in the excited T1-states namely.For these compounds with electron-accepting NO2-groups the non-radiative deactivation of S1- and T1-states (by ∼2-3orders of magnitude compared to mesophenyl substituted OEP) is observed upon the displacement of NO2-group frompara- and meta- to ortho-position of the phenyl ring being the maximal one for ortho-case and minimal in meta-case.For orthonitromesophenyl substituted PdOEP it results also in drastic changes of T-T absorption spectra and strongphosphorescence quenching. It was shown that for OEP-Ph(m-NO2) and OEP-Ph(p-NO2) molecules as well as for thedimers with the same substitution, PET processes with the participation of porphyrin S1-state are affected by through-bond interactions and may be considered as bridge-assisted reactions. The highest value kSet= 9.5×109 s−1 of the PET rateconstant was obtained for monomeric ortho-NO2 substituted molecules in toluene at 293 K. In this case steric interactions offlanking bulky substituents favours to the overlap of molecular orbitals for interacting porphyrin, D and nitrogroup, A ( theelectronic coupling V =130-190 cm−1 in dimethylformamide). It results in the direct through-space PET from the porphyrinlocally excited S1-state to the low-lying CT state of the radical ion pair (the “normal” Marcus region, non-adiabatic casepresumably).The T1-state deactivation in porphyrin free bases containing NO2 groups is connected with thermally activated transitionsto upper-lying CT states of the radical ion pair as well as the strengthening of rate constants of non-radiative intersystemcrossing S1 −→T1 , while for the corresponding Pd-complexes the direct PET from the locally excited T1-state to A (within50-70 ps in dimethylformamide at 293 K).

This research was supported by NFBR of Belarus (Grant No 99-104).

C-27

Practical information

• SYMPOSIUM SECRETARIAT:Ms. Katrin Lantsch, room 2 A 7, Thursday and Friday: from 8 a.m. to 4:30 p.m.On Saturday the institute’s main entrance will be open for the symposium from 8a.m. till 3 p.m.

• COMPUTERS:The rooms 2 A 9, 2 A 14, 2 A 16 and 2 A 20 can be used during the symposiumfor reading e-mails. You can login to your account by using a telnet session on anxterminal. Click on “Terminals” and on “New Telnet”.If you have any questions please contact Mr. Goerke (2A 12) in any computing-related question. Help with hardware (terminals, printers) can be obtained fromMr. Deggelmann (2 A 10).

• LIBRARY: our library is a reference library which means that books must remain inthe institute. Please ask Mrs. Nather, our librarian, for details. Journals should notbe taken out of the library. other libraries in Germany. Information concerning thelibrary are available at http://www.mpipks-dresden.mpg.de/publ/library.html,including an on-line catalogue.

• COPY MACHINES: You can use the copy machines in 1C11 and 2C11.

• TELEPHONE CALLS: For private calls you can buy a telephone card at the in-stitute’s reception. It costs DM 10. The next card telephone is at the tram stop“Nothnitzer Strasse”. For business calls please come to office 2 A 7.

• FOR THOSE ACCOMMODATED IN THE GUEST HOUSES:

– Breakfast: is served from 7:30 a.m. onward.

– Guest house keys: you can open each entrance of the institute as well as thelibrary with your guest house key. Within the blue part of the key is a chip,move along the little box at each entrance, after a beep you can open the door.When leaving please drop the guest house keys into the box in the entrancehall of your guest house.

• FOR THOSE ACCOMMODATED IN THE HOTEL OR IN THE GUESTHOUSE“PENSION KAUBLER”:

– Breakfast: is served in the hotel or in the guesthouse

– Keys for entering the institute: please come to room 2 A 7 in order to get one.Please do not forget to give it back before leaving.

• SECURITY: after 6:30 p.m. the entrances of the institute should be locked. Pleasecheck after entering or leaving the institute that the door is correctly shut. Pleaseleave your window shut or tilted, but not open.

1

List of contributors

Artacho Emilio, I-13

Beckmann D., I-15Bezryadin Alexey, I-11Boese Daniel, C-8Bourgoin Jean-Philippe, I-1Brandbyge Mads, C-15Brehmer Ludwig, C-23Bruder Christoph, C-1

Calzolari Arrigo, I-9Choi Mahn-Soo, C-1Cingolani Roberto, I-2Colombi Ciacchi Lucio, C-2Cuniberti Gianaurelio, C-3, C-5

Damle P., I-5Datta S., I-5De Rienzo Francesca, C-4de Vries Simon, I-11Dekker Cees, I-11Deppe Hans, I-3Di Felice Rosa, I-9

Fagas Giorgos, C-3, C-5Fedorets Dmytro, C-6Frauenheim Th., C-21Fritz Torsten, I-4, C-24

Galperin M., I-10Galperin Y. M., C-9Garbesi Anna, I-9Ghosh Avik, I-5Giese Bernd, I-6Goldoni G., C-19Gorelik L. Y., C-6, C-9, C-16Großmann Frank, I-7, C-7Gutierrez Rafael, I-7, C-7

Hansson A., C-22Hjort M., C-22Hofstetter Walter, C-8Howard Judith A.K., C-12Hanggi Peter, I-8

Isacsson Andreas, C-9

Jaziri Sihem, C-10Johansson A, C-22Jonson M., C-6, C-9, C-16

Kampen T.U., C-20Kleinekathofer U., C-11Koehler Th., C-21Koentjoro Olivia, C-12Kondov Ivan, C-11

Leo K., C-24Lindner Th., C-20Low Paul, C-12

Malysheva Lyuba, C-13Mancal T., C-14Manghi F., C-19May Volkhard, C-14Mayor M., I-15Menziani M. C., C-4Mertig Michael, C-2, C-18Mills A. P. Jr., I-14Molinari Elisa, I-9, C-19Mozos Jose Luis, C-15Monch I. M., C-18

Nitzan Abraham, I-10Nord Tomas, C-16

Ochs R., I-15Onipko A. I., C-13Ordejon Pablo, I-13, C-15

Park S., C-20Paulsson M., C-22Petrov Elmar G., I-8, C-14Pickholz Monica, C-17Pohl Anna, C-17Pompe Wolfgang, C-2, C-18Porath Danny, I-11Proehl H., C-24Puschmann Horst, C-12

2

List of contributors

Raithby P., C-25Rakshit T., I-5Reichert J., I-15Richter Jan, C-18Richter Klaus, C-3, C-5Rontani M., C-19Rousseau Roger, C-12

Schackert H. K, C-18Schmidt Rudiger, I-7, C-7Scholz Reinhard, C-20Schreiber M., C-11Scholler Herbert, I-12Segal D., I-10Seidel Ralf, C-2Seifert Gotthard, C-21Sellam F., C-24Shekhter R. I., C-6, C-9, C-16Shevchenko Ye. V., C-14Snaith Tom, C-12Soler Jose M., I-13Stafstrom Sven, C-17Stafstrom Sven, C-22Stephan Jorg, C-23Stokbro Kurt, C-15, C-25

Taylor Jeremy, C-15Thurzo I., C-20Turberfield Andrew, I-14Torker Michael, C-24

v. Lohneysen H., I-15Vinzelberg H., C-18

Walzer Karsten, C-25Weber Heiko, I-15

Yaliraki Sophia, I-16Yurke B., I-14

Zahid F., I-5Zahn D.R.T., C-20Zelinskjj Ya. R., C-14Zenkevich Edward, C-26Zhu Li, I-11

3

List of participants

Stefano Bellucci bellucci@lnf.infn.it +39-6-9403-2888, -2882

Laboratori Nazionali di Frascati +39-6-9403-2427

INFN

Via E. Fermi 40

00044 Frascati

ITALY

Jean-Philippe Bourgoin jbourgoin@cea.fr +33-1-6908-5565

CEA/Saclay Bat.125 +33-1-6908-6640

91191 Gif sur Yvette Cedex

FRANCE

Christoph Bruder christoph.bruder@unibas.ch +41-61-267-3692

Departement Physik und Astronomie +41-61-267-1349

Universitat Basel

Klingelbergstr. 82

4056 Basel

SWITZERLAND

Arrigo Calzolari calzolari.arrigo@unimo.it +39-059-2055257

Dipartimento di Fisica +39-059-367488

Universita di Modena e Reggio Emilia

Via Campi 213/A

41100 Modena

ITALY

Mohamed Lamine Camara e.george@lycos.com +380-50-591-3526

Electromechanics & Physics +380-572-36-4694

Unkrainian Engineerno-pedagogical Academia

Prospect Pobedi, Dom 60A KB-50

61202 Kharkov

UKRAINE

Frank Cichos cichos@physik.tu-chemnitz.de +49-371-531-3066

Institut fur Physik +49-371-531-3060

Technische Universitat Chemnitz

09107 Chemnitz

GERMANY

Roberto Cingolani roberto.cingolani@unile.it +39-832-320562, -320283

Dipartimento di Ingegneria +39-832-326351

dell’Innovazione

Universita di Lecce

Via Arnesano

73100 Lecce

ITALY

4

List of participants

Lucio Colombi Ciacchi lucio@tmfs.mpgfk.tu-dresden.de +49-351-463-1424

Institut fur Werkstoffwissenschaft +49-351-463-1422

Technische Universitat Dresden

Hallwachstr. 3

01069 Dresden

GERMANY

Gianaurelio Cuniberti cunibert@mpipks-dresden.mpg.de +49-351-871-2213

Max-Planck-Institut fur +49-351-871-1999

Physik komplexer Systeme

Nothnitzer Str. 38

01187 Dresden

GERMANY

Francesca De Rienzo derienzo.francesca@unimo.it +39-059-2055091

Chemistry Department +39-059-373543

Universita di Modena e Reggio Emilia

Via Campi 183

41100 Modena

ITALY

Hans Deppe hans.deppe@amd.com +49-351-277-2001

Co-General Manager +49-351-277-9-2001

AMD Saxony Manufacturing GmbH

Wilschdorfer Landstraße 101

01109 Dresden

GERMANY

Rosa Di Felice rosa@unimo.it +39-059-2055301

Dipartimento di Fisica +39-059-367488

Universita di Modena e Reggio Emilia

Via Campi 213/A

41100 Modena

ITALY

George Elochukwu Egbengwu e.george@lycos.com +380-50-591-3526

Electromechanics & Physics +380-572-36-4694

Unkrainian Engineerno-pedagogical Academia

Prospect Pobedi, Dom 60A KB-50

61202 Kharkov

UKRAINE

Giorgos Fagas fagas@mpipks-dresden.mpg.de +49-351-871-2205

Max-Planck-Institut fur +49-351-871-1999

Physik komplexer Systeme

Nothnitzer Str. 38

01187 Dresden

GERMANY

5

List of participants

Dmytro Fedorets dima@fy.chalmers.se +46-31-772-5480

Department of Applied Physics +46-31-41-6984

Chalmers University of Technology

412 96 Goteborg

SWEDEN

Torsten Fritz fritz@iapp.de +49-351-463-4902

Institut fur Angewandte Photophysik +49-351-463-7065

Technische Universitat Dresden

01062 Dresden

GERMANY

Alexander Gaiduk gaiduk@imaph.bas-net.by +375-17-284-1754

Microphotonics Group

Institute of Molecular and Atomic Physics

F. Skaryna Avenue 70

220072 Minsk

BELARUS

Avik Ghosh ghosha@ecn.purdue.edu +1-765-494-3383

1285 Electrical Engineering Department +1-765-494-6441

Purdue University

West Lafayette, IN 47906

USA

Bernd Giese bernd.giese@unibas.ch +41-61-267-1106/1112

Department of Chemistry +41-61-267-1105 or -0976

University of Basel

St. Johanns Ring 19

4056 Basel

SWITZERLAND

Frank Großmann frank@physik.tu-dresden.de +49-351-463-3863

Institut fur Theoretische Physik +49-351-7297

Technische Universitat Dresden

Zellescher Weg 17

01062 Dresden

GERMANY

Martin Guthold guthold@cs.unc.edu +1-919-962-3526

Department of Physics +1-919-962-0480

University of North Carolina

Phillips Hall, CB 3255

Chapel Hill, NC 27599-3175

USA

6

List of participants

Rafael Gutierrez gutie@theory.phy.tu-dresden.de +49-351-463-6151

Institut fur Theoretische Physik

Technische Universitat Dresden

01062 Dresden

GERMANY

Peter Hanggi hanggi@physik.uni-augsburg.de +49-821-598-3250

Institut fur Physik +49-821-598-3222

Universitat Augsburg

Universitatsstr. 1

86135 Augsburg

GERMANY

Matthias Hettler hettler@int.fzk.de +49-7247-82-6433

Institut fur Nanotechnologie +49-7247-82-6434

Forschungszentrum Karlsruhe GmbH

Postfach 3640

76021 Karlsruhe

GERMANY

Walter Hofstetter hofstett@physik.uni-augsburg.de +49-821-598-3707

Theoretische Physik III +49-821-598-3725

Universitat Augsburg

86135 Augsburg

GERMANY

Gert-Ludwig Ingold gert.ingold@physik.uni-augsburg.de +49-821-598-3234

Institut fur Physik +49-821-598-3222

Universitat Augsburg

Universitatsstr. 1

86135 Augsburg

GERMANY

Andreas Isacsson isac@fy.chalmers.se +46-31-772-3151

Department of Applied Physics

Chalmers University of Technology

412 96 Goteborg

SWEDEN

Sihem Jaziri sihem.jaziri@fsb.rnu.tn +216-2-591-906

Departement de Physique +216-2-590-566

Faculte des Sciences de Bizerte

Jarzouna

7021 Bizerte

TUNISIA

7

List of participants

Konstantin Kikoin kikoin@bgumail.bgu.ac.il +972-3-9500085

Physics Department +972-3-6472904

Ben-Gurion University of the Negev

84105 Beer-Sheva

ISRAEL

Denis Klemm denis@tmfs.mpgfk.tu-dresden.de

Institut fur Werkstoffwissenschaft

Technische Universitat Dresden

Hallwachstr. 3

01069 Dresden

GERMANY

Rochus Klesse rk@thp.uni-koeln.de +49-221-470-4300

Institut fur Theoretische Physik +49-221-470-5159

Universitat zu Koln

Zulpicher Str. 77

50937 Koln

GERMANY

Yuriy Klymenko alexo@bitp.kiev.ua, yukid@mail.ru +380-44-266-9146

Space Research Institute +380-44-266-4124

NAS and NSA of Ukraine

40, Acad. Glushkov Prospekt

03187 Kiev

UKRAINE

Sigmund Kohler sigmund.kohler@physik.uni-augsburg.de +49-821-598-3316

Institut fur Physik +49-821-598-3222

Universitat Augsburg

Universitatsstr. 1

86135 Augsburg

GERMANY

Ivan Kondov i.kondov@physik.tu-chemnitz.de +49-371-531-3148

Institut fur Physik +49-371-531-3151

Technische Universitat Chemnitz

09107 Chemnitz

GERMANY

Christophe Krzeminski chk@isen.fr +33-3-2030-4060

IEMN Departement ISEN +33-3-2030-4051

CNRS

41, Boulevard Vauban

59046 Lille

FRANCE

8

List of participants

Paul J. Low p.j.low@durham.ac.uk +44-191-374-3114

Department of Chemistry +44-191-386-1127

University of Durham

South Road

Durham DH1 3LE

UNITED KINGDOM

Lyuba Malysheva malysh@sabbo.net +380-44-213-8779

Institute of Nonlinear Physics in +380-44-241-3956

Condensed Matter

Bogolyubov Institute for Theoretical Physics

Metrologichna, 14b

13143 Kiev

UKRAINE

Volkhard May may@physik.hu-berlin.de +49-30-202-46739

Institut fur Physik +49-30-238-4763

Humboldt-Universitat zu Berlin

Hausvogteiplatz 5 - 7

10117 Berlin

GERMANY

Ingrid Mertig mertig@ptprs2.phy.tu-dresden.de +49-351-463-3854

Institut fur Theoretische Physik +49-351-463-7079

Technische Universitat Dresden

01062 Dresden

GERMANY

M. E. Michel-Beyerle Michel-Beyerle@ch.tum.de +49-89-289-13400

Institut fur Physikalische und +49-89-289-13026

Theoretische Chemie

Technische Universitat Munchen

Lichtenbergstr. 4

85748 Garching bei Munchen

GERMANY

Elisa Molinari molinari.elisa@unimo.it +39-059-205-5284

Dipartimento di Fisica +39-059-374752

Universita di Modena e Reggio Emilia

Via Campi 213/A

41100 Modena

ITALY

Jose Luis Mozos jlm@icmab.es +34-935-801-853

Institut de Ciencia de Materials +34-935-805-729

Consejo Superior de Investigaciones

Cientificas (CSIC)

Campus le la UAB

08193 Bellaterra

SPAIN

9

List of participants

Abraham Nitzan nitzan@post.tau.ac.il +972-3-640-8904

School of Chemistry +972-3-642-3765, 640-9293

Tel Aviv University

Tel Aviv 69978

ISRAEL

Tomas Nord tomas@fy.chalmers.se +46-31-772-3156

Department of Applied Physics +46-31-41-6984

Chalmers University of Technology

412 96 Goteborg

SWEDEN

Monica Pickholz monpi@ifm.liu.se +46-13-281319

Department of Physics, IFM +46-13-137568

Linkoping University

581 83 Linkoping

SWEDEN

Danny Porath porath@star.tau.ac.il +972-58-518827

School of Physics and Astronomy +972-3-6422979

Tel Aviv University

Tel Aviv 69978

ISRAEL

Jan Richter jrichter@tmfs.mpgfk.tu-dresden.de +49-351-463-1465

Institut fur Werkstoffwissenschaft +49-351-463-1422

Technische Universitat Dresden

Hallwachstr. 3

01069 Dresden

GERMANY

Klaus Richter richter@mpipks-dresden.mpg.de +49-351-871-2210

Max-Planck-Institut fur +49-351-871-1999

Physik komplexer Systeme

Nothnitzer Str. 38

01187 Dresden

GERMANY

Herbert Scholler herbert.schoeller@int.fzk.de +49-7247-82-6384

Institut fur Nanotechnologie +49-7247-82-6434/6369

Forschungszentrum Karlsruhe GmbH

Postfach 3640

76021 Karlsruhe

GERMANY

10

List of participants

Reinhard Scholz scholz@physik.tu-chemnitz.de +49-371-531-3145

Institut fur Physik +49-371-531-3143

Technische Universitat Chemnitz

09107 Chemnitz

GERMANY

Gotthard Seifert seifert@phys.uni-paderborn.de +49-5251-60-2331

Fachbereich 6 - Theoretische Physik +49-5251-60-3435

Universitat-GH Paderborn

Warburger Str. 100

33098 Paderborn

GERMANY

Robert Shekhter shekhter@fy.chalmers.se +46-31-772-3667

Department of Applied Physics +46-31-41-6984

Chalmers University of Technology

412 96 Goteborg

SWEDEN

Jose M. Soler jose.soler@uam.es +34-91-397-5155

Departamento del Fisica +34-91-397-3961

de la Materia Condensada

Universidad Autonoma de Madrid

28049 Madrid

SPAIN

Sven Stafstrom sst@ifm.liu.se +46-13-281352

Department of Physics, IFM +46-13-137568

Linkoping University

581 83 Linkoping

SWEDEN

Jorg Stephan jstephan@rz.uni-potsdam.de +49-331-977-1503

Institut fur Physik +49-331-977-1457

Universitat Potsdam

PSF 601553

14415 Potsdam

GERMANY

Michael Torker toerker@iapp.de +49-351-463-3504

Institut fur Angewandte Photophysik +49-351-463-7065

Technische Universitat Dresden

Mommsenstr. 13

01062 Dresden

GERMANY

11

List of participants

Andrew Turberfield a.turberfield@physics.ox.ac.uk +44-1865-272-359

Department of Physics +44-1865-272-400

Clarendon Laboratory

University of Oxford

Parks Road

Oxford OX1 3 PU

UNITED KINGDOM

Alessandro Valli alessandro.valli@amd.com +49-351-277-4543

APC Group +49-351-277-94543

AMD Saxony Manufacturing GmbH

Wilschdorfer Landstr. 101

01109 Dresden

GERMANY

Bart van Wees wees@phys.rug.nl +31-50-363-4933

Department of Applied Physics and +31-50-363-3900

Materials Science Centre

University of Groningen

Nijenborgh 4.13

9747 AG Groningen

THE NETHERLANDS

Christian von Borczyskowski borczyskowski@physik.tu-chemnitz.de +49-371-531-3015

Institut fur Physik +49-371-531-3060

Technische Universitat Chemnitz

Reichenhainerstr. 70

09107 Chemnitz

GERMANY

Karsten Walzer kw@mic.dtu.dk +45-4525-5787

Mikroelektronik Centret +45-4588-7762

Danish Technical University

Oersteds Plads

2800 Lyngby

DENMARK

Heiko B. Weber heiko.weber@int.fzk.de +49-7247-82-6376

Institut fur Nanotechnologie +49-7247-82-6368

Forschungszentrum Karlsruhe GmbH

Postfach 3640

76021 Karlsruhe

GERMANY

Fangqing Xie fangqing.xie@int.fzk.de +49-7247-82-6356

Institut fur Nanotechnologie +49-7247-82-6366

Forschungszentrum Karlsruhe GmbH

Postfach 3640

76021 Karlsruhe

GERMANY

12

List of participants

Sophia N. Yaliraki s.yaliraki@ic.ac.uk +44-20-7594-5732

Department of Chemistry +44-20-7594-5804

Imperial College

Exhibition Road

London SW7 2AY

UNITED KINGDOM

Eduard Zenkevich zenkev@imaph.bas-net.by

Laboratory of Molecular Photonics +375-17-284-0030

Institute of Molecular and Atomic Physics

National Academy of Sciences of Belarus

F. Skaryna Avenue 70

220072 Minsk

BELARUS

13

Max-Planck-Institut fur Physik komplexer Systeme

Dresden, Germany