The elastic constants and specific heats of the alkali metals

Abstract

In a recent paper the author has given a theoretical calculation of the elastic constants of copper and of the alkali metals. The purpose of this note is: firstly, to correct some mistakes in the calculation for the alkali metals (that for copper is correct); secondly, to compare these results with a recent experimental determination of the elastic constants for sodium ; and thirdly, to attempt an explanation of the observed fact that the specific heats of the alkalis show abnormally large deviations from the Debye form. The corrections are as follows: the formulae in Table II, p. 630, for the body centred cubic structure should read A^I - 16/3 ρ dw/dρ 2B^I = 8/9 ρ² d²w/dρ² + 16/9 ρ dw/dρ. In formulae (17a) and (18) a factor 2 should be inserted on the left-hand side, since w is defined as the potential energy per ion, whereas Born and Mayer’s values relate to the energy per pair of ions.