title: Bound excitons in time-dependent density-functional theory: optical and energy-loss spectra.
abstract: A robust and efficient frequency dependent and nonlocal exchange correlation f(xc)(r,r(');omega) 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, SiO2, 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 f(xc) that is fast to evaluate and easy to implement.
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Químicas, UPV/EHU, Centro Mixto CSIC-UPV/EHU and Donostia International Physics Center, E-20018 San Sebastián, Basque Country, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Marini
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Del Sole
authors.forename: Angel
authors.initials: A
authors.lastname: Rubio