IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
artículos
Título:
Exact solution of the two levels system and the Einstein solid in the microcanonical
Autor/es:
BERTOLDI, D. S.; BRINGA, E. M.; MIRANDA, E. N.
Revista:
EUROPEAN JOURNAL OF PHYSICS
Editorial:
IOP PUBLISHING LTD
Referencias:
Lugar: Bristol; Año: 2011 vol. 32 p. 1485 - 1485
ISSN:
0143-0807
Resumen:
The two-level system and the Einstein model of a crystalline solid are taught in every course of statistical mechanics and they are solved in the microcanonical formalism because the number of accessible microstates can be easily evaluated. However, their solutions are usually presented using the Stirling approximation to deal with factorials. In this paper, those two models are solved without any approximation, using the gamma function and its derivatives.  Exact values are calculated for the entropy, temperature and specific heat, and the relative error between our exact solution and the approximate one using the Stirling approximation. This error is significant for small systems, with a number of particles N ¡­ 100, as in studies of atomic clusters or nanoscale structures.
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