Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-principles study of excitonic effects in Raman intensities   The ab initio prediction of Raman intensities for bulk solids usually relies
on the hypothesis that the frequency of the incident laser light is much
smaller than the band gap. However, when the photon frequency is a sizeable
fraction of the energy gap, or higher, resonance effects appear. In the case of
silicon, when excitonic effects are neglected, the response of the solid to
light increases by nearly three orders of magnitude in the range of frequencies
between the static limit and the gap. When excitonic effects are taken into
account, an additional tenfold increase in the intensity is observed. We
include these effects using a finite-difference scheme applied on the
dielectric function obtained by solving the Bethe-Salpeter equation. Our
results for the Raman susceptibility of silicon show stronger agreement with
experimental data compared with previous theoretical studies. For the sampling
of the Brillouin zone, a double-grid technique is proposed, resulting in a
significant reduction in computational effort.

24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg