Extended Koopmans’ Approximation for CASDFT Exchange-Correlation Functional ()
ABSTRACT
A new density functional theory approach based on a
complete active space self-consistent field (CASSCF) reference function in
Extended Koopmans’ approximation is discussed. Recently, the number of
generalizations of density functional theory based on a multiconfigurational
CASSCF reference function with exact exchange (CASDFT) was introduced. It was
shown by one of the authors (Dr. Gusarov) that such a theory could be
formulated by introducing a special form of exchange-correlation potential. To
take into account an active space and to avoid double counting of correlation
energy the dependence from on-top pair density P2(r) as a new
variable was introduced. Unfortunately, this requires a deep review and
reparametrization of existing functional expressions which lead to additional
computational difficulties. The presented approach does not require introducing
additional variables (like on-top pair density, P2(r)) and is based on Extended Koopmans’ theorem (EKT) approximation for
multiconfigurational wave function within CASSCF method.
Share and Cite:
Gusarov, S. and Dmitriev, Y. (2018) Extended Koopmans’ Approximation for CASDFT Exchange-Correlation Functional.
Journal of Applied Mathematics and Physics,
6, 1242-1246. doi:
10.4236/jamp.2018.66104.