Can unrestricted density-functional theory describe open shell singletbiradicals?

Gräfenstein, Jürgen,1963Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry (författare)

Unrestricted density functional theory (UDFT) can be used for the description of open-shell singlet (OSS) biradicals provided a number of precautions are considered. Biradicals that require a two-determinantal wave function (e.g. OSS state of carbenes) cannot be described by UDFT for principal reasons. However, if the overlap between the open-shell orbitals is small (the single electrons are located at different atomic centers) errors become small and, then, the principal failure of UDFT in these cases is not apparent and may even be disguised by the fact that UDFT has the advantage of describing spin polarization better than any restricted open shell DFT method. In the case of OSS biradicals with two- or multiconfigurational character (but a one-determinantal form of the leading configuration), reasonable results can be obtained by broken-symmetry (BS)-UDFT, however in each case this has to be checked. In no case is it reasonable to lower the symmetry of a molecule to get a suitable UDFT description. Hybrid functionals such as B3LYP perform better than pure DFT functionals in BS-UDFT calculations because the former reduce the self-interaction error of DFT exchange functionals, which mimics unspecified static electron correlation effects, so that the inclusion of specific static electron correlation effects via the form of the wavefunction becomes more effective.

Kraka, ElfiGothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry (författare)
Filatov, MichaelGothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry (författare)
Cremer, Dieter,1944Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry (författare)
Göteborgs universitetInstitutionen för kemi (creator_code:org_t)

Ingår i:International Journal of Molecular Sciences: MDPI AG3, s. 360-3941422-0067

Av författaren/redakt...: Gräfenstein, Jür ...; Kraka, Elfi; Filatov, Michael; Cremer, Dieter, ...

Om ämnet

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.