Empirical tight binding parameters for GaAs and MgO with explicit basis through DFT mapping

TL;DR

This paper introduces a DFT-based mapping method to derive explicit tight binding parameters and basis functions for GaAs and MgO, improving accuracy over traditional fitting methods and enhancing atomistic device simulations.

Contribution

It presents a novel DFT mapping approach to construct TB parameters and explicit basis functions for GaAs and MgO, addressing limitations of traditional ETB methods.

Findings

GaAs TB parameters show better agreement with DFT in bulk band structure.

Different indirect valleys observed in nanowire calculations using DFT-derived parameters.

MgO TB parameters and basis functions successfully obtained through the new method.

Abstract

The Empirical Tight Binding(ETB) method is widely used in atomistic device simulations. The reliability of such simulations depends very strongly on the choice of basis sets and the ETB parameters. The traditional way of obtaining the ETB parameters is by fitting to experiment data, or critical theoretical bandedges and symmetries rather than a foundational mapping. A further shortcoming of traditional ETB is the lack of an explicit basis. In this work, a DFT mapping process which constructs TB parameters and explicit basis from DFT calculations is developed. The method is applied to two materials: GaAs and MgO. Compared with the existing TB parameters, the GaAs parameters by DFT mapping show better agreement with the DFT results in bulk band structure calculations and lead to different indirect valleys when applied to nanowire calculations. The MgO TB parameters and TB basis functions are also obtained through the DFT mapping process.