Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonextensive thermodynamics of a cluster consisting of $M$ Hubbard
  dimers ($M=1,2,3$ and $\infty$)   The thermodynamical property of a small cluster including $M$ Hubbard dimers,
each of which is described by the two-site Hubbard model, has been discussed
within the nonextensive statistics (NES). We have calculated the temperature
dependence of the energy, entropy, specific heat and susceptibility for $M = 1,
2, 3$ and $\infty$, assuming the relation between the entropic index $q$ and
the cluster size $N$ given by $q=1+2/N$ ($N = 2 M$ for $M$ dimers), which was
previously derived by several methods. For relating the physical temperature
$T$ to the Lagrange multiplier $\beta$, two methods have been adopted: $T=1/k_B
\beta$ in the method A [Tsallis {\it et al.} Physica A {\bf 261} (1998) 534],
and $T=c_q/k_B \beta$ in the method B [Abe {\it et al.} Phys. Lett. A {\bf 281}
(2001) 126], where $k_B$ denotes the Boltzman constant, $c_q= \sum_i p_i^q$,
and $p_i$ the probability distribution of the $i$th state. The susceptibility
and specific heat of spin dimers described by the Heisenberg model have been
discussed also by using the NES with the methods A and B. A comparison between
results calculated by the two methods suggests that the method B may be better
than the method A for small-scale systems.

25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc