Time-dependent density functional theory beyond Kohn–Sham Slater determinants
Autor: | Neepa T. Maitra, Michael Ruggenthaler, Soeren E. B. Nielsen, Johanna I. Fuks |
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Jazyk: | angličtina |
Rok vydání: | 2016 |
Předmět: |
Chemical Physics (physics.chem-ph)
010304 chemical physics Physical system General Physics and Astronomy Kohn–Sham equations FOS: Physical sciences Time-dependent density functional theory State (functional analysis) 01 natural sciences Adiabatic theorem Physics - Chemical Physics 0103 physical sciences Physics::Atomic and Molecular Clusters Slater determinant Density functional theory Statistical physics Physical and Theoretical Chemistry Physics::Chemical Physics 010306 general physics Adiabatic process Mathematics |
Zdroj: | Physical Chemistry Chemical Physics |
Popis: | 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 $v_{xc}^s$, 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. Comment: 11 pages, 9 Figures. submitted for special invited issue honoring Evert Jan Baerends, in Phys. Chem. Chem. Phys. (2016) |
Databáze: | OpenAIRE |
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