Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First principles calculation of vibrational Raman spectra in large
  systems: signature of small rings in crystalline SiO2   We present an approach for the efficient calculation of vibrational Raman
intensities in periodic systems within density functional theory. The Raman
intensities are computed from the second order derivative of the electronic
density matrix with respect to a uniform electric field. In contrast to
previous approaches, the computational effort required by our method for the
evaluation of the intensities is negligible compared to that required for the
calculation of vibrational frequencies. As a first application, we study the
signature of 3- and 4-membered rings in the the Raman spectra of several
polymorphs of SiO2, including a zeolite having 102 atoms per unit cell.

8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat