Journal of Physical Chemistry A, Vol.110, No.22, 7189-7196, 2006
Ab initio diradical/zwitterionic polarizabilities and hyperpolarizabilities in twisted double bonds
We investigated the nature of the ground state and static response properties ( A, R, and,) 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 are orders of magnitude smaller than those predicted by semiempirical methods.