UC Berkeley

The nuclear strong force, which binds the nucleons within an atomic nucleus, is a van der Waals force. A consequence of this is that the phenomenon of liquid-vapor phase coexistence occurs in the nuclear system. The experimental means of constructing the nuclear phase diagrams rely heavily on the thermodynamics of cluster theories, theories that historically have not served in many practical applications. In this thesis I explore the validity of the ideal cluster law and the Fisher droplet model in systems where the phase diagrams are known from traditional means.

For molecular fluids, I show that the phase coexistence of a wide variety of systems can be described using the Fisher theory. This study is closely related to the study of an extended principle of corresponding states. These considerations demonstrates the utility of the Fisher droplet model in describing liquid-vapor phase coexistence of van der Waals fluids.

For model systems, I show that the physical clusters of the Lennard-Jones model at coexistence can be used to construct the phase diagrams of the fluid. The connection between the physical clusters and the thermodynamic properties of the vapor are established using the ideal cluster law. Furthermore, the cluster concentrations are well described by the Fisher droplet model. These considerations lead to an alternative construction of the phase diagrams for the Lennard-Jones system.

The success of cluster theories to describe properties of liquid-vapor coexistence that are already well established demonstrates the validity of applying these concepts to construct the nuclear phase diagrams.