title: Undoing static correlation: long-range charge transfer in time-dependent density-functional theory.
abstract: Long-range charge-transfer excited states are notoriously badly underestimated in time-dependent density-functional theory (TDDFT). We discuss how exact TDDFT captures charge transfer between open-shell species: in particular, the role of the step in the ground-state potential, and the severe frequency dependence of the exchange-correlation kernel. An expression for the latter is derived, that becomes exact in the limit that the charge-transfer excitations are well separated from other excitations. The exchange-correlation kernel has the task of undoing the static correlation in the ground state introduced by the step, in order to accurately recover the physical charge-transfer states.
authors: Department of Physics and Astronomy, City University of New York and Hunter College, 695 Park Avenue, New York, New York 10021, USA. nmaitra@hunter.cuny.edu
authors: Neepa T
authors: NT
authors: Maitra