Thermal expansion of sodium and potassium

Abstract

Thermal expansion for sodium and potassium has been calculated at all temperatures using realistic potentials, obtained from one-orthogonalized-plane-wave matrix elements and screening functions of Geldart and Taylor and of Vashishta and Singwi. No significant difference between the results from these two potentials has been found. The agreement with recent experimental results of Schouten and Swenson for potassium is found to be good. In the absence of appropriate experimental data for sodium, the theoretical results have been compared with the old data on polycrystalline sodium. These are found to be in qualitative agreement.