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Contacts with insulators (ionic crystals, rare gases…) Structure and low energy dynamics Irradiation dynamics. Hierarchical method for the dynamics of clusters and molecules in contact with an environment. Molecules/clusters + environment (embedded/deposited) - PowerPoint PPT Presentation
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Hierarchical method for the dynamics of clusters and
molecules in contact with an environment
Molecules/clusters + environment
(embedded/deposited)
Fundamental studies on mechanisms
(Nano)Technological applications (size controlled
deposition…)
M. Baer, P. G. Reinhard (Erlangen), M. Dinh, ES (Toulouse)
Contacts with insulators (ionic crystals, rare gases…) Structure and low energy dynamicsIrradiation dynamics
Density Functional Theory (DFT)
Ensemble of orbitals (1 electron) / no correlation
One body density
Effective mean field theory (Kohn-Sham)
Model for free clusters
Explicit ions via pseudo potentials
Detail of structure + ionic Molecular Dynamics (MD)
Ions
Electrons
Kohn-Sham potential Ions + ext.
Local Density Approximation (LDA)
Exch. + Corr. Hartree
Self Interaction Correction (SIC)
Time Dependent (TD)LDA TDSIC !?
Metal cluster in an environment
Hierarchical approach:Model for free clusters +Polarizable matrix+ Couplings
Atoms Ar, Ne, Kr, MgO…
RI
Ions Na, K (Cs, Ag…)
Equations of motion by variationof total energyTDLDA for electrons
MD for ions
MD for atoms (positions AND dipoles)
Electrons i
Dipoles
Positions
@MgONa6
freeOptical response
Delicate balanceShort range compression (blue)Long range polarization (red)
Exp: Rostock
Optical response (cont’d)C
om
pre
ssio
n
Polarization Caution: « Helium blue shift »
More detailed investigations …
Na – Na ~ 800 meVAr – Ar ~ 50 meVNa -Ar ~ 5 meV
Response of environment Na6@Ar(100) Ekin = 800 meV
Charge
Distribution of dipole energy at time of impact
x [a0]
Key role of environment’s degrees of freedomSubtle energy exchanges
▶ Some open questions
Towards irradiation dynamics Clusters and « bio » molecules under irradiation (laser, ions…)
Formal difficulties SIC and beyond…, TDSIC…
Some conclusions and perspectives
▶ Low energy response of cluster’s in contact with an
environment
Hierarchical model
Microscopic electrons, classical polarization… (QM/MM)Delicate interplay of competing effects
Subtle energy balance
Key role of environment’s degrees of freedom