Analytical screened form factor obtained from Bachelet, Hamann and Schluter pseudopotential I

Abstract

Model-(Pseudo)potential method has proven to be an interesting technique for calculating electronic properties in the framework of Ziman [1] formula for pure liquid metals and Faber-Ziman [2] expression for liquid alloys. First principle model-potentials are non local and their parameters are energy dependent. In the alloy one must take into account an energy dependent effective mass, a depletion hole and the Fermi energy core shift which is not known for alloys. More, the thermopower includes explicitely an energy dependent contribution. The first principle model-(pseudo)potential of BACHELET, HAMANN and SCHLUTER ( B.H.S.) [3] is energy independent and avoids the necessity of making these corrections. {itWe have used this potential to calculate analytically the corresponding form factor which is given in this paper (this paper : paper I). The resistivity and the thermopower of pure germanium and gallium and of the germanium-gallium alloy has been measured and calculated by using the FABER-ZIMAN [2] formalism. Both hard sphere and experimental structure factors have been used (when available). The agreement between experimental and calculated properties can be considered as good and confirms that the B.H.S. [3] model-potential is adequate for describing liquid alloys electronic properties. The discussion is made in paper II [4]. The transferability of B.H.S. potential allows us to use it for alloys and to compute the alloy effective interatomic potential. The results are compared with those obtained from the local screened non local ANIMALU model potential ( S.M.P.) and with pure metal results. These results are discussed in paper III [5].