Quantum chemistry methods were applied to compute and analyze the nonlinear optical (NLO) properties of the monomers and dimers for anion-radicals TCNQ^－ and their copper-salts. It is found that, the α_s values decrease as a function of the introductive Cu^＋ into TCNQ^－ and the various positions of Cu^＋ have different effects on NLO coefficients. The polarizabilities of the dimers are related to their binding energies, the geometrical configurations for dimers influence the second-order NLO coefficients as well. From the frontier molecular orbit composition, the third-order NLO coefficients dependence of the charge transfer degree can be found, the overlapping between two conjugated planes also has a contribution.

Key words: anion-radical TCNQ^－, CuTCNQ, NLO properties, theoretical computation