Band gaps of crystalline solids from Wannier-localization-based optimal tuning of a screened range-separated hybrid functional

Accurate prediction of fundamental band gaps of crystalline solid-state systems entirely within density functional theory is a long-standing challenge. Here, we present a simple and inexpensive method that achieves this by means of nonempirical optimal tuning of the parameters of a screened range-separated hybrid functional. The tuning involves the enforcement of an ansatz that generalizes the ionization potential theorem to the removal of an electron from an occupied state described by a localized Wannier function in a modestly sized supercell calculation. The method is benchmarked against experiment for a set of systems ranging from narrow band-gap semiconductors to large band-gap insulators, spanning a range of fundamental band gaps from 0.2 to 14.2 electronvolts (eV), and is found to yield quantitative accuracy across the board, with a mean absolute error of similar to 0.1 eV and a maximal error of similar to 0.2 eV.

Automated summary

This study presents a simple and inexpensive method to accurately predict fundamental band gaps of crystalline solid-state systems. The method, based on nonempirical optimal tuning of a screened range-separated hybrid functional, has been benchmarked against experiment and found to yield quantitative accuracy across a range of systems.