Temperature and Volume Dependence of the Electrical Resistivity of Sodium and Potassium

Abstract

The temperature dependence of the electrical resistivity of sodium and potassium is calculated both at constant pressure and at constant volume for the following extensive temperature range: for sodium from 50°K to the melting point, and for potassium from 20°K to the melting point. Excellent agreement with experiment is obtained. It is found that the significant difference between the constant-pressure and the constant-volume temperature dependences of the resistivity is completely explained by explicitly taking into account anharmonic effects on the phonon spectrum and on the polarization vectors. The contribution due to the volume dependence of the screened electron-ion-interaction matrix elements is also included.