Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Pressure-induced softening as a common feature of framework structures
  that have negative thermal expansion
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol