Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Three-Body Problem   An improved hyperspherical harmonic method for the quantum three-body problem
is presented to separate three rotational degrees of freedom completely from
the internal ones. In this method, the Schr\"{o}dinger equation of three-body
problem is reduced to a system of linear algebraic equations in terms of the
orthogonal bases of functions. As an important example in quantum mechanics,
the energies and the eigenfunctions of some states of the helium atom and the
helium-like ions are calculated.

27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin