Virial Expansion for a Classical Hard Sphere Plasma in the Low Density Limit

This talk will be devoted to some recent calculations of the density expansion of the thermodynamical functions for a classical multicomponent system made of charged particles interacting via the hard sphere Coulomb potential. The general method of this virial expansion has been already studied in previous papers [1-3] in the more general situation of a quantum Coulomb plasma. Here, the diagrammatic expansion is the analog of the familiar Abe-Meeron [4,5] expansion for a classical one-component plasma. The exact density expansion of the free energy and of the pressure are explicitly calculated up to the power of density rho^(5/2). The corresponding expressions include, in a systematic and coherent way, the contributions of the various physical effects such as corrections beyond the Debye screening and creation of dipolar pairs. Long range correction terms proportional to rho^(p/2)*log(rho) (p=4,5) have been also derived and indicate the behavior of the Coulomb potential in the mechanism of pair creation. The range of validity of this expansion is controlled by selective rules preventing the collapse of big neutral entities.

[1] A. Alastuey and A. Perez, Europhys. Lett. 20, 19 (1992)
[2] A. Alastuey, F. Cornu and A. Perez, Phys. Rev. E 51, 1725 (1995)
[3] A. Alastuey and A. Perez, Phys. Rev. E 53, 5714 (1996)
[4] R. Abe, Progr. Theor. Phys. 22, 213 (1959)
[5] E.Meeron, J. Chem. Phys. 28, 630 (1958)