Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermostatistics of small systems: Exact results in the microcanonical
  formalism   Several approximations are made to study the microcanonical formalism that
are valid in the thermodynamics limit. Usually it is assumed that: 1)Stirling
approximation can be used to evaluate the number of microstates; 2) the surface
entropy can be replace by the volumen entropy; and 3)derivatives can be used
even if the energy is not a continuous variable. It is also assumed that the
results obtained from the microcanonical formalism agree with those from the
canonical one. However, it is not clear if these assumptions are right for very
small systems (10-100 particles). To answer this questions, two systems with
exact solutions (the Einstein model of a solid and the two-level system)have
been solve with and without these approximations.

10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas