Download presentation
Presentation is loading. Please wait.
1
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 dynamics Irradiation dynamics
2
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 potentialIons + ext. Local Density Approximation (LDA) Exch. + Corr.Hartree Self Interaction Correction (SIC) Time Dependent (TD)LDA TDSIC !?
3
Metal cluster in an environment Hierarchical approach: Model for free clusters + Polarizable matrix + Couplings Atoms Ar, Ne, Kr, MgO… RIRI Ions Na, K (Cs, Ag…) Equations of motion by variation of total energy TDLDA for electrons MD for ions MD for atoms (positions AND dipoles) Electrons i Dipoles Positions
4
@MgO Na 6 free Optical response Delicate balance Short range compression (blue) Long range polarization (red)
5
Exp: Rostock Optical response (cont’d) Compression Polarization Caution: « Helium blue shift » More detailed investigations …
6
Na – Na ~ 800 meV Ar – Ar ~ 50 meV Na -Ar ~ 5 meV Response of environment Na 6 @Ar(100) E kin = 800 meV Charge Distribution of dipole energy at time of impact x [a 0 ] Key role of environment’s degrees of freedom Subtle energy exchanges
![Na – Na ~ 800 meV Ar – Ar ~ 50 meV Na -Ar ~ 5 meV Response of environment Na E kin = 800 meV Charge Distribution of dipole energy at time of impact x [a 0 ] Key role of environment’s degrees of freedom Subtle energy exchanges](http://images.slideplayer.com/35/10310885/slides/slide_6.jpg "Na – Na ~ 800 meV Ar – Ar ~ 50 meV Na -Ar ~ 5 meV Response of environment Na E kin = 800 meV Charge Distribution of dipole energy at time of impact x [a 0 ] Key role of environment’s degrees of freedom Subtle energy exchanges")
7
▶ 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
Similar presentations
