EXTENSIONS OF THE QUASI-GAUSSIAN ENTROPY THEORY

In this paper we present the quasi-Gaussian entropy theory in a compre hensive and consistent way, introducing a new derivation of the theory very suited for applications to molecular systems, and addressing its use in the case of multi-phase systems. A general derivation of the p ossible confinement of the system within a part of phase space is give n, and for water it is shown that for this a hard sphere excluded volu me model can be used. To obtain the temperature dependence of the pres sure, a new differential equation is derived, and besides the previous ly introduced Gaussian and Gamma states, in this paper we also describ e a new statistical state, the Inverse Gaussian state. We discuss the properties of these different statistical states and for water compare their thermodynamics with experimental data, finding that both the Ga mma and Inverse Gaussian states are excellent descriptions. (C) 1997 A merican Institute of Physics.