Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The most stable isomer of H$_2$C$_4$-(OCS)$_2$ van der Waals complex:
  Theory and experiment agree on a structure with C2 symmetry   We report the infrared spectrum of H$_2$C$_4$-(OCS)$_2$ trimer in the region
of the nu1 fundamental vibration of the OCS monomer. The van der Waals
complexes are generated in a supersonic slit-jet apparatus and probed using a
rapid-scan tunable diode laser. Both H$_2$C$_4$-(OCS)$_2$ and
D$_2$C$_4$-(OCS)$_2$ are studied. Analysis of their spectra establishes that
the trimer has C$_2$ point group symmetry. Theoretical calculations performed
to find stationary points on the potential energy surface confirm that the
observed structure is the most stable form. The experimental rotational
parameters are in very good agreement with those computed using double hybrid
functionals.

24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
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
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex