Electrical resistivity and thermoelectric power of molten gallium: Theory versus experiment

Abstract

We present our new accurate measurements on the electrical resistivity and thermopower of liquid gallium as a function of temperature. To interpret our experimental data we used, for the first time to our knowledge (earlier calculations used the pseudopotential formalism), ab initio calculations of the electrical resistivity ρ(E) and of the thermoelectric power Q(E) of liquid gallium as functions of energy. This formalism has the great advantage of including a full-energy dependent calculation of the thermopower. To construct the phase shifts we used the experimental pair correlation function. To calculate the resistivity and thermopower we used both the structure factor obtained experimentally and that calculated with hard spheres. The results are compared and discussed. Various potentials based on the Hartree-Fock formalism and using different exchange contributions have been used. Overall agreement between calculation and experiment is obtained. It seems, however, that the Kohn-Sham value of the X-α Slater approximation gives results closer to experiment than the Slater value for both resistivity and thermopower. Subsequently, the problem of the sign of the thermopower of liquid metals is discussed and explained.