Second hyperpolarizabilities (gamma) of bisimidazole and bistriazole benezenes: Diradical character, charged state and spin state dependences

The second hyperpolarizabilities of bisimidazole- and bistriazole-benzene compounds are calculated at different levels of approximation to unravel the effects of diradical character as well as of charge and spin multiplicity. A discussion is presented on the diradical character and the spin state control of third-order nonlinear optical properties of diradical molecular systems.