TY - JOUR
KW - paper
AU - Fabien Bruneval
AU - Francesco Sottile
AU - Olevano V
AU - Lucia Reining
AB - 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\textquoterights 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. (c) 2006 American Institute of Physics.
BT - J. Chem. Phys.
CY - CIRCULATION \& FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA
DA - APR 14
DO - 10.1063/1.2186996
M1 - 14
N2 - 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\textquoterights 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. (c) 2006 American Institute of Physics.
PB - AMER INST PHYSICS
PP - CIRCULATION \& FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA
PY - 2006
EP - 144113
T2 - J. Chem. Phys.
TI - Beyond time-dependent exact exchange: The need for long-range correlation
UR - http://dx.doi.org/10.1063/1.2186996
VL - 124
ER -