New Approach to Calculating Electronic Band Structure of Bi2Te3: Parametrized Tight-Binding Corrections to Density Functional Theory Wannier Hamiltonian

Bi₂Te₃ has been recognized as the most promising material for thermoelectric applications near room temperature. Common density functional theory (DFT) methods do not accurately predict its electronic band structure near the Fermi level. The maximally localized Wannier approach [1] properly reproduces the DFT bands, whereas traditional parameterized tight-binding models, while incorporating experimental knowledge, are limited to a small number of parameters and unable to precisely describe all aspects of the band properties. To correct these deficiencies, we combine the strengths of both approaches, modifying the DFT Wannier Hamiltonian with small corrections, that are transferred to the matrix elements in a consistent way from an intuitively simple parameterized tight-binding form. In this hybrid approach, the DFT single-particle Hamiltonian is considered as the baseline, and effective corrections are added to its matrix elements to fine-tune the bands near the Fermi energy. Our method can be generalized to other systems, including Bi₂Te₃-based alloys, estimating carrier effective masses and alloy scattering to identify the optimal alloy composition for thermoelectric performance.

1. N. Marzari, et al., Review of Modern Physics 84 (2012)