Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A comparative study of the low energy HD+o-/p-H2 rotational
  excitation/de-excitation collisions and elastic scattering   The Diep and Johnson (DJ) H$_2$-H$_2$ potential energy surface (PES) obtained
from the first principles [P. Diep, K. Johnson, J. Chem. Phys. 113, 3480
(2000); 114, 222 (2000)], has been adjusted through appropriate rotation of the
three-dimensional coordinate system and applied to low-temperature ($T<300$ K)
HD+$o$-/$p$-H$_2$ collisions of astrophysical interest. A non-reactive quantum
mechanical close-coupling method is used to carry out the computation for the
total rotational state-to-state cross sections $\sigma_{j_1j_2\rightarrow
j'_1j'_2}(\epsilon)$ and corresponding thermal rate coefficients
$k_{j_1j_2\rightarrow j'_1j'_2}(T)$. A rather satisfactory agreement has been
obtained between our results computed with the modified DJ PES and with the
newer H$_4$ PES [A.I. Boothroyd, P.G. Martin, W.J. Keogh, M.J. Peterson, J.
Chem. Phys. 116, 666 (2002)], which is also applied in this work. A comparative
study with previous results is presented and discussed. Significant differences
have been obtained for few specific rotational transitions in the H$_2$/HD
molecules between our results and previous calculations. The low temperature
data for $k_{j_1j_2\rightarrow j'_1j'_2}(T)$ calculated in this work can be
used in a future application such as a new computation of the HD cooling
function of primordial gas, which is important in the astrophysics of the early
Universe.

7
The categories of this paper are: hep-th
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess