Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Derivation of the Density Functional via Effective Action   A rigorous derivation of the density functional in the Hohenberg-Kohn theory
is presented. With no assumption regarding the magnitude of the electric
coupling constant $e^2$ (or correlation), this work provides a firm basis for
first-principles calculations. Using the auxiliary field method, in which $e^2$
need not be small, we show that the bosonic 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. The
excitations of the many-particle system can be obtained within the same
formalism. We also explicitly demonstrate at zero-temperature the
single-particle limit, the weak-coupling limit of the energy functional, and
its application to homogeneous electron gas.

16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom