  We present a theoretical study of the structural, electronic and transport
properties of bulk Bi2Te3 within density functional theory taking into account
the van der Waals interactions (vdW) and the quasiparticle self-energy
corrections. It is found that the optB86b-vdW functional can well reproduce the
experimental lattice constants and interlayer distances for Bi2Te3. Based on
the fully optimized structure, the band structure of Bi2Te3 is obtained from
first-principles calculations with the GW approximation and the Wannier
function interpolation method. The global band extrema are found to be off the
high-symmetry lines, and the real energy band calculated is in good agreement
with that measured experimentally. In combination with the Boltzmann theory,
the GW calculations also give accurate prediction of the transport properties,
and the calculated thermoelectric coefficients of Bi2Te3 almost coincide with
the experimental data.
