Theoretical Study on Second Hyperpolarizabilities of Diradical Systems
Masayoshi Nakano, Ryohei Kishi, Nozomi Nakagawa, Tomoshige Nitta, Takashi Kubo, Kazuhiro Nakasuji, Kenji Kamada, Koji Ohta, Benoit Champagne, Edith Botek and Kizashi Yamaguchi
We investigate the static second hyperpolarizabilities () of singlet diradical molecules, i.e., 1,4-bis-(imidazole-2-ylidene)-cyclohexa-2,5-diene (BI2Y) and related molecule (BI2YN), by the ab initio molecular orbital and hybrid density functional theory calculations. It is found that the value of BI2Y with intermediate diradical character is about one-order as large as that of BI2YN with very small diradical character.