Abstract: The nonlinear second-order optical susceptibilities β_x of some substituted benzenes: aniline, nitrobenzene, o-nitroaniline, p-nitroaniline and 2,4-dinitroaniline were calculated. Then the effects of charge transfer between substituted groups on molecular nonlinear second-order optical susceptibilities were discussed. The conclusion is thatβ′=β_add+β_ct is not a good formula for the calculation of β, although the idea of contribution of charge transfer between substituted groups for β is still a considerable useful concept.

Key words: p-Nitrioaniline, Configuration interaction, Nonlinear second-order optical susceptibility