Publication details for Prof. David J. TozerTozer, David J. & Peach, Michael J. G. (2018). Molecular excited states from the SCAN functional. Molecular Physics 116(11): 1504-1511.
- Publication type: Journal Article
- ISSN/ISBN: 0026-8976 (print), 1362-3028 (electronic)
- DOI: 10.1080/00268976.2018.1453094
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
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.