Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The novel aspect of hydrogen atom: the fine structure and spin can be
  derived by single component wavefunction   The fine structure of hydrogen energy was calculated by using the usual
momentum-wavefunction relation directly, rather than establishing the
well-known Dirac wave equation. As the results, the energy levels are
completely the same as that of the Dirac wave equation, while the wavefunction
is single component that is quite different from Dirac's four component
wavefunction, the most important thing is that the present calculation brings
out electronic spin in a new way which has never been reported and indicates
that the electronic spin is a kind of orbital motion.

19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas