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

The longitudinal static second hyperpolarizabilities gamma 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 gamma are elucidated by using the gamma density analysis. Remarkable differences in the gamma values and their density distributions are observed for different charged states of these systems. (C) 2000 Elsevier Science B.V. All rights reserved.