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HL: Fachverband Halbleiterphysik
HL 46: Optical Properties
HL 46.3: Vortrag
Donnerstag, 20. März 2025, 10:15–10:30, H15
Nonempirical hybrid functional based on metaGGA — •Stefan Riemelmoser1, Xun Xu1,2, and Alfredo Pasquarello1 — 1École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland — 2Beijing Computational Science Research Center, Beijing, China
Semi-local density functionals such as PBE typically underestimate experimental band gaps by 50%. Hybrid functionals address this "band gap problem" by admixing a fraction of exact exchange to semi-local exchange. The optimal mixing parameter depends on the specific material and can be identified as the inverse dielectric constant. Recently, we have show that dielectric constants obtained using the r2SCAN metaGGA functional are significantly more accurate than dielectric constants obtained using PBE. This can be understood through the improved treatment of electronic self-interaction within the metaGGA framework.
In this talk, we will show that a dielectric-dependent hybrid functional based on r2SCAN can outperform the standard PBE based hybrid in terms of band gaps. Particularly impressive improvements are obtained for narrow gap semiconductors such as Ge and InAs, where PBE wrongly predicts a metallic phase, but r2SCAN can open a gap. The hybrid functional based on r2SCAN also yields accurate effective masses and ionization potentials. Finally, we showcase that our new hybrid functional is an excellent choice for semiconductor applications such as defect calculations.
Keywords: hybrid functional; metaGGA; semiconductor; band gap; dielectric constant