Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 26: Methods: Electronic Structure Theory

O 26.4: Talk

Tuesday, February 26, 2008, 12:00–12:15, MA 042

Constrained adiabatic DFT modeling nonadiabatic behavior - simple and effective — •Matthias Timmer and Peter Kratzer — Fachbereich Physik, Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany

Non-adiabatic effects, in our case the creation of electron-hole pairs, become more and more accessible in theoretical calculations, and they have long been observed experimentally in, e.g., the detection of chemicurrents. We present a new method to calculate the excitation spectrum of electron-hole pairs in adsorption on metals for adatoms which have an initial spin magnetic moment. To accomplish this we use a mapping of the system onto a bosonic Hamiltonian. Starting from adiabatic DFT calculations we calculate the classical trajectory of the adatom. This trajectory can be used to calculate the nonadiabatic occupations of the adiabatic Kohn-Sham states. Nonadiabaticity is originating from spin relaxation effects. In order to describe this relaxation, the spin degree of freedom is treated explicitly within the density matrix formalism. A projection on the adsorbate orbitals is then used to change the occupation of the adiabatic KS states in a way that guarantees the obtained spin polarization localized at the adatom. By treating the spin up and spin down case separately, and by using the density of states, we get separate energy spectra for the spin up and spin down case, and for electrons and holes, which is novel for these computationally fast adiabatic DFT calculations. As an example, we apply our method to the system H on Al(111). We compare our results to previous TDDFT and model calculations.