F. Quarati^1,* and P. Quarati²

¹ Dipartimento di Fisica, Universitá di Cagliari, I-09042 Monserrato, Italy.
E-mail: [email protected]
² Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy, and Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, I-09042 Monserrato, Italy.
E-mail: [email protected]
^* Present address: Dept. of Physics and Astronomy, University of Glasgow, Scotland, U.K.

Received: 25 July 2002 / Accepted: 31 March 2003 / Published: 30 June 2003

Abstract: We calculate the phase space volumeoccupied by a nonextensive system of N classical particles described by an equilibrium (or steady-state, or long-term stationary state of a nonequilibrium system) distribution function, which slightly deviates from Maxwell-Boltzmann (MB) distribution in the high energy tail. We explicitly require that the number of accessible microstates does not change respect to the extensive MB case. We also derive, within a classical scheme, an analytical expression of the elementary cell that can be seen as a macrocell, different from the third power of Planck constant. Thermodynamic quantities like entropy, chemical potential and free energy of a classical ideal gas, depending on elementary cell, are evaluated. Considering the fractional deviation from MB distribution we can deduce a physical meaning of the nonextensive parameter q of the Tsallis nonextensive thermostatistics in terms of particle correlation functions (valid at least in the case, discussed in this work, of small deviations from MB standard case).

PACS codes: 05.20.-y, 05.70.-a

Keywords: Classical Statistical Mechanics, Thermodynamics.