Spin State Dependence of Second Hyperpolarizabilities of Diradical Molecules
Yohei Kishi, Masayoshi Nakanda, Nozomi Nakagawa, Tomoshige Nitta, Kenji Kamada, Koji Ohta, Benoit Champagne, Edith Botiek and Kizashi Yamaguchi
Ab initio MO and density functional theory calculations are applied to the investigation of the relationship between the spin state and the second hyperpolarizabilities () of diradical molecules, singlet and triplet 1-4-bis-(imidazol-2-ylidene)-cyclohexa-2,5-diene (BI2Y). The value of the diradical molecule with intermediate diradical character in the singlet state is turned out to be significantly reduced in the triplet state due to the Pauli principle.