Keith W. Johnson’s research while affiliated with Lawrence Livermore National Laboratory and other places

The two computer methods of Monte Carlo and lattice dynamics are used to determine fluid and face‐centered‐cubic solid thermodynamic properties for classical particles interacting with pairwise‐additive inverse 4th, 6th, and 9th power potentials. These results, together with those already on hand for 12th power and hard‐sphere potentials, provide a complete, and remarkably simple, description of the dependence of the pure‐phase thermodynamics and the melting transition on the “softness” of the pair potential.

This paper reports the results of self-consistent calculations on aluminum of the total energy, bulk modulus, and band structure by the augmented-plane-wave method. Using a Kohn-Sham free-electron exchange we calculate a 0\ifmmode^\circ\else\textdegree\fi{}K equilibrium volume 5.8% greater than observed and a compressibility too large by 16%. We find that a free-electron exchange factor of 0.713\ifmmode\pm\else\textpm\fi{}0.01 would predict the correct 0\ifmmode^\circ\else\textdegree\fi{}K equilibrium density.

The pressure and entropy for soft-sphere particles interacting with an inverse twelfth-power potential are determined using the Monte Carlo method. The solid-phase entropy is calculated in two ways: by integrating the single-occupancy equation of state from the low density limit to solid densities, and by using solid-phase Monte Carlo pressures to evaluate the anharmonic corrections to the lattice-dynamics high-density limit. The two methods agree, and the entropy is used to locate the melting transition. The computed results are compared with the predictions of the virial series, lattice dynamics, perturbation theories, and cell models. For the fluid phase, perturbation theory is very accurate up to two-thirds of the freezing density. For the solid phase, a correlated cell model predicts pressures very close to the Monte Carlo results.