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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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      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:
      ID Code: 124473
      Deposited By: ep_importer_pure
      Deposited On: 12 Apr 2018 16:10
      Refereed?: Yes
      Published?: Published
      Last Modified: 20 Mar 2019 01:09
      Identification Number:

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