Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bound on the Group Velocity of an Electron in a 1D Periodic Potential   By using a recently derived upper bound on the allowed equilibrium current in
a ring, it is proved that the magnitude of the group velocity of a Bloch
electron in a one-dimensional periodic potential is always less than or equal
to the group velocity of the same Bloch state in an empty lattice. Our
inequality also implies that each energy band in a one-dimensional crystal
always lies below the corresponding free-electron band, when the minima of
those bands are aligned.

7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs