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Bound excitons in time-dependent density-functional-theory: optical and energy-loss spectra

A. Marini, R. Del Sole, A. Rubio

cond-mat.mtrl-sciarXiv:cond-mat/0310495

Abstract

A robust and efficient frequency dependent and non-local exchange-correlation fxc(r,r';ω) is derived by imposing time-dependent density-functional theory (TDDFT) to reproduce the many-body diagrammatic expansion of the Bethe-Salpeter polarization function. As an illustration, we compute the optical spectra of LiF, and diamond and the finite momentum transfer energy-loss spectrum of LiF. The TDDFT results reproduce extremely well the excitonic effects embodied in the Bethe-Salpeter approach, both for strongly bound and resonant excitons. We provide a working expression for fxc that is fast to evaluate and easy to implement.

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