Doping metallic chemically active nanocontacts:

Pt H2Auand in a environment.

Yamila.García

Applied Physics Department, Alicante University,Spain

Is the interpretation of current experiments in molecular electronics beyond the reach of standard (LDA)

first-principles-transport-calculations?

2. H2 act as a local dopant on Pt and Au nanocontacts:

Our numerical results & experimental information.

1. ≠Ab-initio DFT:

Remarks & Outline:

Single Molecule Devices:

VI

∂∂

=G

( ) [ ]−+= GΓGΓ RLTrET

0=V

towards an electronic characterization

( )EThe22

= : Landauer Formalism

FE

ab-initio calculations

2- Atomic configurations3- Model for the electrodes

Quantum Chemistry tools for 4- Basis sets

5- The method: HF,DFT,…,FCI

1- Experimental set up

0=T

Left electrode Right electrode

Bulk + + Bulk Nanojunction

Energetic alignment at the contact

Left electrode Right electrodeBulk + + Bulk Nanojunction

HOMO

LUMO

GAPFermi level Fermi level

atomos/molecules

GAP

Energetic alignment at the contact

FCI

LDA

GGA

MGGA

+ =Hybrid Methods

hLDA

hGGA

hMGGA

B3LYP

3.93.8Ni

3.83.6MnO

7.37.8MgO

3.23.4ZnO

1.51.4GaAs

5.85.5Diamond

3.83.5Si

B3LYPExp.Material

BAND GAPS [eV]

J.Muscat,A.Wander,N.M.Harrison, Chem.Phys.Lett,342 (2001) 397-401

Q u

a l

i t y

HF

Wave Function Density Functional

For a numerical solution of the many-body–electronic problem

GAP GAP GAP

DOS [arb.units] DOS [arb.units]

[E-EFerm

i ] eVCO

ND

UCT

ANCE

[2 e

2/h

]

[E-EFermi] eV

an attempt to explain the evolution of spectral densities

LDA or B3LYP?That is the question.

R.H.M. Smit,Y.Noat,C.Untiedt,N.D.Lang,M.van Hemert,J.M.vanRuitenbeek, Nature 419, 906 (2002)

0.

0.8

0.6

0.4

0.2

Pt/H2

Pt

0 1 2 3 4 5

Num

ber o

f cou

nts

Conductance (2e2/h)

The smallest molecular bridge?

Zone d(PtPt)[nm]

G[2e2/h]

1 27 1.0

2 50 0.2

1 2

~ ~

SINGLE Molecule Chemistry

Doping:H2 charging a Pt nanocontact.

[E-EFermi] eV

CO

ND

UCT

ANCE

[2 e

2/h

]

d-orbitals contribution at the contact

Pt contact

Pt doped contact

DO

S [a

rb.u

nits

]

0 0.3-0.3[E-EFermi] eV

• Conductance

• Directionality

Remarks:

Sz.Czonka, A.Halbritter,G.Mihaly, Cond-Mat/0502421

Conductance (2e2/h)

Num

ber o

f cou

nts

1 2 3

1 2 3

Au

Au/H2

The smallest molecule vs. the noblest metal

3

Zone d(AuAu)[nm]

G[2e2/h]

1 24 1.0

2 28 0.2-0.5

3 36 0

~ ~

SINGLE Molecule Chemistry

1 2

Doping:H2 disturb a Au nanocontact.

CO

ND

UCT

ANCE

[2 e

2/h

]

[E-EFermi] eV

s-orbitals contribution in the chain

Au chain

Au doped chain

DO

S [a

rb.u

nits

]

[E-EFermi] eV-0.3 0.30

Remarks:

• Conductance

• Directionality

Future Work

• Inelastic scattering events• Large size molecules• Finite bias• Finite temperature• …..

In collaboration with:

J.J. Palacios

E. Louis

E. SanFabián

A. J. Pérez-Jiménez

J. A. Vergés

Applied Physics Department,Alicante University,Spain

Applied Physics Department,Alicante University,Spain

Physical-Chemistry Department,Alicante University,Spain

Physical-Chemistry Department,Alicante University,Spain

Materials Science Institute of Madrid, Spain

ADEU BARCELONA