Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An extension of the Kubo-Greenwood formula for use in molecular
  simulations   We discuss the foundations and extend the range of applicability of the
widely used Kubo-Greenwood formula (KGF) for the electronic conductivity. The
conductivity is derived from the current density, and only the probability
amplitude rather than the transition probability is used. It is shown that the
contribution to the conductivity from degenerate states in a low or zero
frequency external electric field and the contribution from states near
resonance with a finite frequency external field are finite. The improved
conductivity expression does not include the familiar "energy conserving" delta
function, and no artificial broadening parameter for delta function is required
for the DC limit. We explored two methods of computing current density. We
discuss the role of many-electron statistics in computing the conductivity in
single-particle approximations, and we show that the conventional KGF is due to
the contribution from single-particle excited states.

2
The categories of this paper are: math
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph