Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical matrix method for quantum periodic potentials   A numerical matrix methodology is applied to quantum problems with periodic
potentials. The procedure consists essentially in replacing the true potential
by an alternative one, restricted by an infinite square well, and in expressing
the wave functions as finite superpositions of eigenfunctions of the infinite
well. A matrix eigenvalue equation then yields the energy levels of the
periodic potential within an acceptable accuracy. The methodology has been
successfully used to deal with problems based on the well-known Kronig-Penney
(KP) model. Besides the original model, these problems are a dimerized KP
solid, a KP solid containing a surface, and a KP solid under an external field.
A short list of additional problems that can be solved with this procedure is
presented.

3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom