Critical Point of Metals from the van der Waals Model

The classical van der Waals model of fluids is modified by a more accurate equation of state for hard spheres. The hard-sphere diameter and the van der Waals constant $a$ are obtained from experimental data. The model is used to predict the critical constants of metals, as well as the equation of state, cohesive energy, and coexistence curves near the critical point. The model is also applied to rare gases and ionic salts. The semiquantitative predictions of the model are at least as accurate as those of other theories. Of the three critical constants, the critical temperature is most accurately predicted, being within 11% of experiment. More information about the interatomic potential in metals is needed before the theory can be substantially improved.