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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 44: 2D Materials

CPP 44.2: Vortrag

Freitag, 21. März 2025, 11:45–12:00, H34

Efficient DFT Band Gap Correction for 2D-Covalent Organic Frameworks Towards Hybrid Functional Level — •Laura Fuchs and Frank Ortmann — Technische Universität München, TUM School of Natural Sciences

Density functional theory (DFT) is the workhorse computational tool for predicting the structure and physical properties of inorganic and organic molecules as well as semiconductors. Unfortunately, the optical and fundamental band gaps are not well described by semi-local DFT approaches. In particular, common DFT methods like the local density approximation (LDA) and the generalized gradient approximation (GGA) severely underestimate the fundamental band gaps, which is commonly referred to as the "band gap problem". However, the correct band gap is of utmost importance for evaluating the suitability of materials such as organic semiconductors for applications like photocatalysis or green energy harvesting. Besides highly expensive many-body perturbation theory, hybrid functionals can address the band gap problem. However, these functionals still involve high computational costs and, for large two-dimensional covalent organic frameworks (2D-COFs), these efforts are not always feasible. Here, we study the relation between semi-local PBE and hybrid HSE06 functionals and present a simple and computationally cheap scheme to extrapolate the PBE band gaps in 2D-COFs to a more precise band gap at HSE06 level.

Keywords: density functional theory (DFT); covalent organic frameworks (COFs); band gap correction