Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Density functional theory and beyond for real materials II

O 55.6: Vortrag

Mittwoch, 24. März 2010, 16:15–16:30, H34

Nonadiabatic electron dynamics in time-dependent reduced-density-matrix functional theory — •Ryan Requist and Oleg Pankratov — University of Erlangen-Nuremberg, Erlangen, Germany

Numerical simulation of real-time electron dynamics in strongly-driven molecules and confined environments remains a challenging problem for ab initio electronic structure methods. One of the most widely used methods is the adiabatic extension of the local density approximation (ALDA) in TD DFT. Although it often works well in linear response calculations, it performs poorly for charge transfer excitations and is unable to account for excitations of doubly-excited character. Progress toward describing these excitations has been made in time-dependent reduced-density-matrix functional theory, which uses the one-body reduced density matrix as the basic variable. This theory might have advantages for real-time dynamics as well. However, a nontrivial obstacle to applying the adiabatic extension approximation has been identified. Namely, the adiabatic extension of the available ground-state functionals leads incorrectly to time-independent occupation numbers (the eigenvalues of the one-body reduced density matrix). In this talk, we describe an adiabatic approximation [arXiv:0911.0945] that generates time-dependent occupation numbers. Tests for a model system demonstrate that it captures quite well Landau-Zener transitions and Stueckelberg oscillations, which are canonical nonadiabatic effects in real-time dynamics. Electron correlation is found to play a crucial role.