Low-temperature electrical and thermal resistivities of potassium and copper: A study of DMR

The low-temperature electrical and thermal resistivities of potassium and copper are numerically calculated. Electron-phonon and electron-impurity scattering mechanisms are included in the Boltzmann equation formalism. The variational method to determine the resistivities and their deviations from Matthiessen's rule (DMR) is utilized. For the calculation of resistivities and DMR in potassium a one orthogonalized-plane-wave model (10PW) and a Born-von Karman force constant phonon spectrum were used. The results are in good agreement with experiment. In the calculation for copper, a 20PW model and a Born-von Karman force constant phonon spectrum were used. The results are found to be an order of magnitude higher than the experimentally observed values. It is concluded that the use of the 20PW model, and the Moriarty form factor, are responsible for the poor agreement.