Variational calculations of excited states via direct optimization of the orbitals in DFT

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dc.contributorHáskóli Íslandsen_US
dc.contributorUniversity of Icelanden_US
dc.contributor.authorLevi, Gianluca
dc.contributor.authorIvanov, Aleksei
dc.contributor.authorJónsson, Hannes
dc.contributor.departmentRaunvísindastofnun (HÍ)en_US
dc.contributor.departmentScience Institute (UI)en_US
dc.contributor.departmentRaunvísindadeild (HÍ)en_US
dc.contributor.departmentFaculty of Physical Sciences (UI)en_US
dc.contributor.schoolVerkfræði- og náttúruvísindasvið (HÍ)en_US
dc.contributor.schoolSchool of Engineering and Natural Sciences (UI)en_US
dc.date.accessioned2021-01-27T12:44:14Z
dc.date.available2021-01-27T12:44:14Z
dc.date.issued2020-06
dc.descriptionPost-print (lokagerð höfundar)en_US
dc.description.abstractA direct optimization method for obtaining excited electronic states using density functionals is presented. It involves selective convergence on saddle points on the energy surface representing the variation of the energy as a function of the electronic degrees of freedom, thereby avoiding convergence to a minimum and corresponding variational collapse to the ground electronic state. The method is based on an exponential transformation of the molecular orbitals, making it possible to use efficient quasi-Newton optimization approaches. Direct convergence on a target nth-order saddle point is guided by an appropriate preconditioner for the optimization as well as the maximum overlap method. Results of benchmark calculations of 52 excited states of molecules indicate that the method is more robust than a standard self-consistent field (SCF) approach especially when degenerate or quasi-degenerate orbitals are involved. The method can overcome challenges arising from rearrangement of closely spaced orbitals in a charge-transfer excitation of the nitrobenzene molecule, a case where the SCF fails to converge. The formulation of the method is general and can be applied to non-unitary invariant functionals, such as self-interaction corrected functionals.en_US
dc.description.sponsorshipThe present work was funded by the Icelandic Research Fund (grant number 196070-052) and the University of Iceland Research Fund. AVI is supported by a doctoral fellowship from the University of Iceland.en_US
dc.description.versionPeer Revieweden_US
dc.format.extent448-466en_US
dc.identifier.citationLevi, G., Ivanov, A. V., & Jónsson, H. (2020). Variational calculations of excited states via direct optimization of the orbitals in DFT. Faraday Discussions, 224(0), 448-466. doi:10.1039/D0FD00064Gen_US
dc.identifier.doiDOI:10.1039/d0fd00064g
dc.identifier.issn1359-6640
dc.identifier.issn1364-5498 (eISSN)
dc.identifier.journalFaraday Discussionsen_US
dc.identifier.urihttps://hdl.handle.net/20.500.11815/2418
dc.language.isoenen_US
dc.publisherRoyal Society of Chemistry (RSC)en_US
dc.relation.ispartofseriesFaraday Discussions;224
dc.relation.urlhttp://pubs.rsc.org/en/content/articlepdf/2020/FD/D0FD00064Gen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectEfnafræðien_US
dc.titleVariational calculations of excited states via direct optimization of the orbitals in DFTen_US
dc.typeinfo:eu-repo/semantics/articleen_US

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