title: Ab initio diradical/zwitterionic polarizabilities and hyperpolarizabilities in twisted double bonds.
abstract: We investigated the nature of the ground state and static response properties (mu, alpha, and beta) for a promising class of twisted pi-electron system nonlinear optical chromophores at the HF, B3LYP, MP2, and CASSCF levels. We report results for a substituted twisted ethylene and a larger tictoid analogue. Previous work has reported only a zwitterionic character for such tictoid species, however, (14,13) CASSCF calculations predict a ground-state diradical. At the HF, B3LYP, MP2, and (14,13) CASSCF levels, the values of beta are orders of magnitude smaller than those predicted by semiempirical methods.
authors.affiliation: Department of Chemistry, University of Washington, Seattle, 98195-1700, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Isborn
authors.forename: Ernest R
authors.initials: ER
authors.lastname: Davidson
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Robinson