$Bi_2Te_3$: Implications of the rhombohedral k-space texture on the   evaluation of the in-plane/out-of-plane conductivity anisotropy
  Different computational scheme for calculating surface integrals in anisotropic Brillouin zones are compared. The example of the transport distribution function (plasma frequency) of the thermoelectric Material \BiTe near the band edges will be discussed. The layered structure of the material together with the rhombohedral symmetry causes a strong anisotropy of the transport distribution function for the directions in the basal (in-plane) and perpendicular to the basal plane (out-of-plane). It is shown that a thorough reciprocal space integration is necessary to reproduce the in-plane/out-of-plane anisotropy. A quantitative comparison can be made at the band edges, where the transport anisotropy is given in terms of the anisotropic mass tensor. 
Peter Zahn, Nicki F. Hinsche, Bogdan Y. Yavorsky, Ingrid Mertig
cond-mat.mtrl-sci