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Article Dans Une Revue Journal of Chemical Physics Année : 2006

Beyond time-dependent exact-exchange : the need for long-range correlation.

Résumé

In the description of the interaction between electrons beyond the classical Hartree picture, bare exchange often yields a leading contribution. Here we discuss its effect on optical spectra of solids, comparing three different frameworks: time-dependent Hartree-Fock, a recently introduced combined density-functional and Green's function approaches applied to the bare exchange self-energy, and time-dependent exact exchange within time-dependent density-functional theory (TD-EXX). We show that these three approximations give rise to identical excitonic effects in solids; these effects are drastically overestimated for semiconductors. They are partially compensated by the usual overestimation of the quasiparticle band gap within Hartree-Fock. The physics that lacks in these approaches can be formulated as screening.We show that the introduction of screening in TD-EXX indeed leads to a formulation that is equivalent to previously proposed functionals derived from many-body perturbation theory. It can be simulated by reducing the long-range part of the Coulomb interaction: this produces absorption spectra of semiconductors in good agreement with experiment.
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Dates et versions

hal-00358798 , version 1 (04-02-2009)

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  • HAL Id : hal-00358798 , version 1

Citer

F. Bruneval, F. Sottile, Valério Olevano, L. Reining. Beyond time-dependent exact-exchange : the need for long-range correlation.. Journal of Chemical Physics, 2006, 124, pp.144113. ⟨hal-00358798⟩
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