Ab initio study of excited state electronic circular dichroism. Two prototype cases: Methyl oxirane and R-(+)-1,1 '-bi(2-naphthol)
2011 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 134, no 24Article in journal (Refereed) Published
A computational approach to the calculation of excited state electronic circular dichroism (ESECD) spectra of chiral molecules is discussed. Frequency dependent quadratic response theory is employed to compute the rotatory strength for transitions between excited electronic states, by employing both a magnetic gauge dependent and a (velocity-based) magnetic gauge independent approach. Application is made to the lowest excited states of two prototypical chiral molecules, propylene oxide, also known as 1,2-epoxypropane or methyl oxirane, and R-(+)-1,1'-bi(2-naphthol), or BINOL. The dependence of the rotatory strength for transitions between the lowest three excited states of methyl oxirane upon the quality and extension of the basis set is analyzed, by employing a hierarchy of correlation consistent basis sets. Once established that basis sets of at least triple zeta quality, and at least doubly augmented, are sufficient to ensure sufficiently converged results, at least at the Hartree-Fock self-consistent field (HF-SCF) level, the rotatory strengths for all transitions between the lowest excited electronic states of methyl oxirane are computed and analyzed, employing HF-SCF, and density functional theory (DFT) electronic structure models. For DFT, both the popular B3LYP and its recently highly successful CAM-B3LYP extension are exploited. The strong dependence of the spectra upon electron correlation is highlighted. A HF-SCF and DFT study is carried out also for BINOL, a system where excited states show the typical pairing structure arising from the interaction of the two monomeric moieties, and whose conformational changes following photoexcitation were studied recently with via time-resolved CD.
Place, publisher, year, edition, pages
2011. Vol. 134, no 24
ab initio calculations, circular dichroism, density functional theory, electron correlations, excited states, HF calculations, molecular configurations, molecular electronic states, molecule-photon collisions, optical rotation
IdentifiersURN: urn:nbn:se:kth:diva-36887DOI: 10.1063/1.3602219ISI: 000292331900012OAI: oai:DiVA.org:kth-36887DiVA: diva2:431503
QC 201107202011-07-202011-07-182011-07-20Bibliographically approved