On the second hyperpolarizabilities γ of three charged states of tetrathiapentalene and tetrathiafulvalene: a γ density analysis

The longitudinal static second hyperpolarizabilities γ for neutral, cation radical and dication states of symmetric condensed-ring and alternant conjugated systems, i.e. tetrathiapentalene and tetrathiafulvalene, are calculated by the use of a density functional method with an extended basis set. The spatial contributions of electrons to γ are elucidated by using the γ density analysis. Remarkable differences in the γ values and their density distributions are observed for different charged states of these systems.