Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamical Properties of the Antiferromagnetic Heisenberg Model in
  Dimensions d=1,2,3   The evolution equation for the expectation values of the Boltzmann factor
between valence bond states is evaluated in lowest order of the dimer cluster
expansion. Explicit formulas are given for the internal energy and the specific
heat of the d-dimensional antiferromagnetic Heisenberg model.

17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga