Molecular excited states from the SCAN functional

Tozer, David J.; Peach, Michael J.G.

Abstract

The performance of the strongly constrained and appropriately normed (SCAN) meta-generalised gradient approximation exchange–correlation functional is investigated for the calculation of time-dependent density-functional theory molecular excitation energies of local, charge-transfer and Rydberg character, together with the excited potential energy curve in H2. The SCAN results frequently resemble those obtained using a global hybrid functional, with either a standard or increased fraction of exact orbital exchange. For local excitations, SCAN can exhibit significant triplet instability problems, resulting in imaginary triplet excitation energies for a number of cases. The Tamm–Dancoff approximation offers a simple approach to improve the situation, but the excitation energies are still significantly underestimated. Understanding the origin of these (near)-triplet instabilities may provide useful insight into future functional development.

Citation

Tozer, D. J., & Peach, M. J. (2018). Molecular excited states from the SCAN functional. Molecular Physics, 116(11), 1504-1511. https://doi.org/10.1080/00268976.2018.1453094

• Journal Article Type: Article
• Acceptance Date: Mar 2, 2018
• Online Publication Date: Apr 8, 2018
• Publication Date: Apr 8, 2018
• Deposit Date: Apr 16, 2018
• Publicly Available Date: Apr 8, 2019
• Journal: Molecular Physics
• Print ISSN: 0026-8976
• Electronic ISSN: 1362-3028
• Publisher: Taylor and Francis Group
• Peer Reviewed: Peer Reviewed
• Volume: 116
• Issue: 11
• Pages: 1504-1511
• DOI: https://doi.org/10.1080/00268976.2018.1453094
• Public URL: https://durham-repository.worktribe.com/output/1334432