First-Principles Calculation of the Electronic Transport Properties of Metals

Abstract

properties are directly related to the topology of the Fermi surface. In particular, in semi-metal and narrow gap semi-conductor systems, a small amount of electron/hole doping will cause dramatic change in the transport properties. The recent development of highly accurate electronic structure calculation methods and new techniques for band fitting enable us to explore potential candidates of novel materials from first-principles calculations. We have implemented a band interpolation scheme to the WIEN97 full-potential linearized augmented plane-wave (LAPW) band structure package 6), 7) to investigate the electronic transport properties of metals and alloy. The electronic transport coefficients are calculated from Fermi surface integration of the quantities related to band structure, e.g., density of states, Fermi velocity and effective mass tensor. In order to obtain these quantities, we used the modified Shankland-Koelling-Wood (SKW) band interpolation scheme 9) with a simple filtering technique. We applied low-pass filtering function to the interpolation equation in order to suppress high frequency wiggles appearing near band crossing points. The detailed procedure of the calculation will be described in a future paper. 10) The calculated and experimentally observed Hall coefficient for several cubic metals are listed in Table I. Previous theoretical results obtained from tight-binding calculations 8) are also tabulated for comparison. As shown in Table I, the overall agreement between present calculations and experiments is very good except for Fe. In the case of Fe, the band crossing near the ∆ point causes high frequency wiggles in the second derivative of the Fermi surface, which give rise to large numerical error in the unfiltered Hall coefficient. This problem is corrected by the filtering procedure. Figure 1 and 2 show calculated carrier concentration nH and Seebeck coefficient S for β � Sb3Zn4. It is experimentally observed that this compound has highly efficient thermoelectric power measured by a dimensionless figure of merit ZT = σS 2 T/ κ, where σ, T and κ correspond to electrical conductivity, temperature and thermal conductivity, respectively. The non-stoichiometric site occupation number of the compound is taken into account by a rigid band model, i.e., the Fermi level obtained by the calculation for stoichiometric composition is shifted by an amount of +0.027 Ry which yields experimentally observed carrier concentration nH =0 .05 hole/cell. Present result for the Seebeck coefficient shows excellent agreement with experiment and other theoretical calculation. 11) We observed that the calculated thermopower for this compound is very sensitive to the doping level(high hole doping