The $X\alpha$ exchange approximation was used in self-consistent augmented-plane-wave calculations on metallic copper. The value assigned to $\alpha$ (0.7225) was chosen to yield zero pressure at the experimentally determined lattice spacing, and the calculations were carried out for six different lattice parameters. The total energy as a function of lattice parameter, resulting from these calculations, was used to determine pressure as a function of lattice parameter, cohesive energy, and compressibility. The cohesive-energy calculation gave 0.286 Ry, which is within 11% of the experimental value of 0.257 Ry. The compressibility, as calculated for two sets of calculated pressure as a function of lattice parameter, was found to agree with the experimental value to within 7% for one set of pressures and to within 4% for the other.

• Received 9 July 1973

DOI:https://doi.org/10.1103/PhysRevB.8.5391