Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dielectric matrix formulation of correlation energies in the Random
  Phase Approximation (RPA): inclusion of exchange effects   Starting from the general expression for the ground state correlation energy
in the adiabatic connection fluctuation dissipation theorem (ACFDT) framework,
it is shown that the dielectric matrix formulation, which is usually applied to
calculate the direct random phase approximation (dRPA) correlation energy, can
be used for alternative RPA expressions including exchange effects. Within this
famework, the ACFDT analog of the second order screened exchange (SOSEX)
approximation leads to a logarithmic formula for the correlation energy similar
to the direct RPA expression. Alternatively, the contribution of the exchange
can be included in the kernel used to evaluate the response functions. In this
case the use of an approximate kernel is crucial to simplify the formalism and
to obtain a correlation energy in logarithmic form. Technical details of the
implementation of these methods are discussed and it is shown that one can take
advantage of density fitting or Cholesky decomposition techniques to improve
the computational efficiency; a discussion on the numerical quadrature made on
the frequency variable is also provided. A series of test calculations on
atomic correlation energies and molecular reaction energies shows that exchange
effects are instrumental to improve over direct RPA results.

34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga