Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A useful form of the recurrence relation between relativistic atomic
  matrix elements of radial powers   Recently obtained recurrence formulae for relativistic hydrogenic radial
matrix elements are cast in a simpler and perhaps more useful form. This is
achieved with the help of a new relation between the $r^a$ and the $\beta r^b$
terms ($\beta$ is a $4\times 4$ Dirac matrix and $a, b$ are constants) in the
atomic matrix elements.

1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas