Electronic properties of IV-VI semiconductors obtained with G₀W₀ including off-diagonal corrections

The computation of electronic properties of IV-VI semiconductors constitutes a challenge for traditional density functional theory (DFT) methods. The underestimation of the bang gap by DFT can lead, in these materials, to a spurious band gap inversion that hinders the characterization of their electronic properties, and therefore the modeling of their thermoelectric performance. In addition, the G₀W₀ approach often used to correct the DFT band structure also fails because of its perturbative nature, making necessary to improve the starting wavefunctions (e.g. using hybrid DFT) or to use more sophisticated approaches such as quasiparticle self-consistent GW. Here instead we use traditional DFT+G₀W₀ with corrections from the relevant off-diagonal elements of the self-energy in order to obtain the band structure of some of these materials, e.g. PbTe. This method, which does not require adjustable parameters, is utilized to extract from first principles band structure characteristics necessary for the calculation of transport coefficients. Band gaps, effective masses and deformation potentials are obtained in good agreement and at a fraction of the computational cost of more sophisticated methods.