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Time-dependent density functional theory beyond Kohn–Sham Slater determinants

MPS-Authors
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Nielsen,  Søren Ersbak Bang
Theory Group, Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;
Center for Free-Electron Laser Science & Department of Physics, Luruper Chaussee 149, 22761 Hamburg, Germany;
Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria;

/persons/resource/persons30964

Ruggenthaler,  Michael
Theory Group, Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;
Center for Free-Electron Laser Science & Department of Physics, Luruper Chaussee 149, 22761 Hamburg, Germany;
Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria;

Fulltext (public)

1603.01176v2.pdf
(Preprint), 782KB

Supplementary Material (public)
There is no public supplementary material available
Citation

Fuks, J. I., Nielsen, S. E. B., Ruggenthaler, M., & Maitra, N. T. (2016). Time-dependent density functional theory beyond Kohn–Sham Slater determinants. Physical Chemistry Chemical Physics, 18(31), 20976-20985. doi:10.1039/C6CP00722H.


Cite as: http://hdl.handle.net/11858/00-001M-0000-002B-2083-8
Abstract
When running time-dependent density functional theory (TDDFT) calculations for real-time simulations of non-equilibrium dynamics, the user has a choice of initial Kohn–Sham state, and typically a Slater determinant is used. We explore the impact of this choice on the exchange–correlation potential when the physical system begins in a 50 : 50 superposition of the ground and first-excited state of the system. We investigate the possibility of judiciously choosing a Kohn–Sham initial state that minimizes errors when adiabatic functionals are used. We find that if the Kohn–Sham state is chosen to have a configuration matching the one that dominates the interacting state, this can be achieved for a finite time duration for some but not all such choices. When the Kohn–Sham system does not begin in a Slater determinant, we further argue that the conventional splitting of the exchange–correlation potential into exchange and correlation parts has limited value, and instead propose a decomposition into a “single-particle” contribution that we denote vSxc, and a remainder. The single-particle contribution can be readily computed as an explicit orbital-functional, reduces to exchange in the Slater determinant case, and offers an alternative to the adiabatic approximation as a starting point for TDDFT approximations.