Equation of State Computations

Abstract

A logical computation method is suggested for approximating the thermodynamic properties of a simple molecular system. In this method the thermodynamic functions of a nonequilibrium system are computed exactly. The state of the system is then varied at fixed volume and temperature so as to give a minimum Helmholtz free energy, consistent with such conditions as are imposed to permit the exact computation. The condition under which this method leads to self‐consistent equations is discussed. The method is then applied in a way that is very close to the Lennard‐Jones and Devonshire cell method, but with cells of variable size. The distribution within a cell is assumed to be Gaussian. The method is numerically far easier than the cell method, and apparently somewhat better.