Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beyond time-dependent exact-exchange: the need for long-range
  correlation   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 functions approach 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.

14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph