Theoretical study of the second hyperpolarizabilities of three charged states of pentalene. A consideration of the structure-property correlation for the sensitive second hyperpolarizability

The static second hyperpolarizabilities (gamma) for neutral, anion radical and dianion states for a symmetric condensed-ring conjugated system, i.e. pentalene, are calculated by the use of ab initio molecular orbital methods with extended basis sets. The dependence of electron correlation effects on gamma is investigated by using the hyperpolarizability density analysis. Remarkable differences in the gamma and the characteristics of the spatial contributions of gamma densities are observed for different electron correlation results and for different charged states of this system.