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

Autor: Neepa T. Maitra, Michael Ruggenthaler, Soeren E. B. Nielsen, Johanna I. Fuks
Jazyk: angličtina
Rok vydání: 2016
Předmět:
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