Some aspects of the calculation of lattice energies

Some relations between lattice energies calculated from various simple equations are pointed out. It is found that these equations give values of the variation of compressibility with pressure that agree poorly with experiments, at least for sodium and cesium chloride, bromide, and iodide. Equations which take this variation into account are developed, and it is found that calculated values of the lattice energy vary very little with the exact equation used. On the whole these extended equations give better agreement between the calculated and observed lattice energies.