Molecular excited states from the SCAN functional

Tozer, David J. and Peach, Michael Joseph George (2018) Molecular excited states from the SCAN functional. Molecular Physics, 116 (11). pp. 1504-1511. ISSN 0026-8976

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Abstract

The performance of the strongly constrained and appropriately normed (SCAN) [Phys. Rev. Lett. 115, 036402 (2015)] meta-generalised gradient approximation exchange–correlation functional is investigated for the calculation of time-dependent density-functional theory (TDDFT) molecular excitation energies of local, charge-transfer, and Rydberg character, together with the excited 3Σ+u 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.

Item Type:
Journal Article
Journal or Publication Title:
Molecular Physics
Additional Information:
This is an Accepted Manuscript of an article published by Taylor & Francis in Molecular Physics on 08/04/2018, available online: http://www.tandfonline.com/10.1080/00268976.2018.1453094
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100/3104
Subjects:
ID Code:
124473
Deposited By:
Deposited On:
12 Apr 2018 15:10
Refereed?:
Yes
Published?:
Published
Last Modified:
29 Nov 2020 05:12