Nonunique fraction of Fock exchange for defects in two-dimensional materials
Abstract
By investigating the vacancy and substitutional defects in monolayer WS with hybrid functionals, we find that there is no unique amount of Fock exchange that concurrently satisfies the generalized Koopmans' condition and reproduces the band gap and band-edge positions. Fixing the mixing parameter of Fock exchange based upon the band gap can lead to qualitatively incorrect defect physics in two-dimensional materials. Instead, excellent agreement is achieved with experiment and many-body perturbation theory within approximation once the mixing parameters are tuned individually for the defects and the band edges. We show the departure from a unique optimized mixing parameter is inherent to two-dimensional systems as the band edges experience a reduced screening whilst the localized defects are subject to bulklike screening.
Keywords
Cite
@article{arxiv.2206.00486,
title = {Nonunique fraction of Fock exchange for defects in two-dimensional materials},
author = {Wei Chen and Sinéad M. Griffin and Gian-Marco Rignanese and Geoffroy Hautier},
journal= {arXiv preprint arXiv:2206.00486},
year = {2022}
}
Comments
Main manuscript (7 pages, 3 figures) with supplemental material (3 pages, 5 figures)