Low-temperature expansions along the gas-solid coexistence curve in lattice gases

In lattice-gas models for which there is no symmetry between low-density (gas) and high-density (solid) phases, the locus of the phase-transition fugacity and transition densities can be determined exactly as a series in the appropriate low-temperature parameter. One equates the low- and high-density fugacity series for the pressure and writes the fugacity as a series in the low-temperature parameter, the resulting equation being a recursion relation for the unknown coefficients. All of the thermodynamic functions can then be evaluated as low-temperature series along both branches of the coexistence curve. With the use of this technique the tricritical parameters of several lattice-gas models are determined.