WanTiBEXOS: A Wannier based Tight Binding code for electronic band structure, excitonic and optoelectronic properties of solids

The Bethe–Salpeter equation (BSE) approach becomes a methodology commonly used for simulating excitonic and optical properties in computer materials sciences. However, BSE approach based directly on first principles demands a high computational cost, being prohibitive for larger systems. In order to overcome this challenge, we have developed WanTiBEXOS, a parallel computational FORTRAN code, constituted of a maximally localized Wannier functions based tight-binding (MLWF-TB) model in conjunction with BSE framework. The MLWF-TB Hamiltonian used in WanTiBEXOS package can be obtained via any density functional theory package interfaced with Wannier90 code. It's expected, due MLWF-TB formalism, a computational time reduction around one or more orders of magnitude in comparison with BSE ab initio implementations. In order to demonstrate its reliability, flexibility, efficiency and versatility of WanTiBEXOS, we simulate electronic and optical property calculations for the representative materials, including conventional bulk semiconductors, perovskites, nano-monolayer materials and van der Waals heterostructures.

贝特-萨尔皮特方程（Bethe–Salpeter equation, BSE）方法现已成为计算材料科学领域模拟激子与光学性质的主流研究方法。然而，直接基于第一性原理的BSE方法计算成本高昂，难以用于较大体系的计算。为解决这一难题，我们开发了WanTiBEXOS——一款并行计算FORTRAN代码，其由基于最大局域化瓦尼尔函数的紧束缚（maximally localized Wannier functions based tight-binding, MLWF-TB）模型与BSE框架结合构建而成。WanTiBEXOS程序包中使用的MLWF-TB哈密顿量，可通过任意与Wannier90代码对接的密度泛函理论程序包获取。得益于MLWF-TB形式体系，相较于从头算BSE实现方案，该方法预计可将计算时间缩短1至数个数量级。为验证WanTiBEXOS的可靠性、灵活性、高效性与通用性，我们针对典型材料体系开展了电子与光学性质计算模拟，涵盖传统块体半导体、钙钛矿、纳米单层材料以及范德瓦尔斯异质结。