Tailoring Electronic Properties of Bi₂Te₃ with Parametrized Tight-Binding Corrections to Density Functional Theory Wannier Matrix Elements

For decades, Bi₂Te₃ has been the best candidate for thermoelectric applications near room temperature. Density functional theory (DFT) fails to reproduce its known experimental features. The maximally localized Wannier approach [1] accurately reproduces the DFT bands, whereas traditional parameterized tight-binding models, while incorporating experimental knowledge, are limited to a small number of parameters and cannot describe all aspects of the bands. To correct these deficiencies, we combine the strengths of each approach, 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 the baseline and 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)