Second hyperpolarizability (γ) of singlet diradical system: Dependence of γ on the diradical character

Masayoshi Nakano, Ryohei Kishi, Tomoshige Nitta, Takashi Kubo, Kazuhiro Nakasuji, Kenji Kamada, Koji Ohta, Benoît Champagne, Edith Botek, Kizashi Yamaguchi

Résultats de recherche: Contribution à un journal/une revueArticle

Résumé

The dependence of the second hyperpolarizability (γ) on the diradical character (γ) for singlet diradical systems is investigated using a model compound, the p-quinodimethane (PQM) molecule with different both-end carbon-carbon (C-C) bond lengths, by several ab initio molecular orbital and density functional theory methods. The diradical character based on UHF calculations indicates that at equilibrium geometry PQM is in a singlet ground state and primarily exhibits a quinoid structure, whereas the diradical character increases when increasing both-end C-C bond lengths. At the highest level of approximation, that is, using the UCCSD(T) method with the 6-31G*+diffuse p (ζ = 0.0523) basis set, the longitudinal static γ of PQM presents a maximum value for intermediate diradical character (y ≈ 0.5) while the γ values are larger for intermediate and large diradical character (y ≈ 0.5-0.7) than for small diradical character (y < 0.2). This feature suggests that the γ values of singlet diradical systems in the intermediate and somewhat strong correlation regimes are significantly enhanced as compared to those in the weak correlation regime. These results are substantiated by a complementary study of the variation in γ upon twisted ethylene.

langue originaleAnglais
Pages (de - à)885-891
Nombre de pages7
journalJournal of physical chemistry A
Volume109
Numéro de publication5
Les DOIs
Etat de la publicationPublié - 10 févr. 2005

Empreinte digitale Examiner les sujets de recherche de « Second hyperpolarizability (γ) of singlet diradical system: Dependence of γ on the diradical character ». Ensemble, ils forment une empreinte digitale unique.

  • Contient cette citation

    Nakano, M., Kishi, R., Nitta, T., Kubo, T., Nakasuji, K., Kamada, K., Ohta, K., Champagne, B., Botek, E., & Yamaguchi, K. (2005). Second hyperpolarizability (γ) of singlet diradical system: Dependence of γ on the diradical character. Journal of physical chemistry A, 109(5), 885-891. https://doi.org/10.1021/jp046322x