Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Density Functional via Effective Action   A rigorous derivation of the density functional via the effective action in
the Hohenberg-Kohn theory is outlined. Using the auxiliary field method, in
which the electric coupling constant $e^2$ need not be small, we show that the
loop expansion of the exchange-correlation functional can be reorganized so as
to be expressed entirely in terms of the Kohn-Sham single-particle orbitals and
energies.

2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
3
The categories of this paper are: physics
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
19
The categories of this paper are: eess