The absorption and resonance Raman excitation profiles of v(4) = 1389 and v(5) = 1195 cm(-1) fundamentals are studied in the excitation region corresponding to the 1(2)B(2g) --> 1(2)B(3u) transition in the tetracyanoquinodimethane (TCNQ) monoanion. Both Franck-Condon (FC) and mode-mixing (Dushinsky) effects in the 1(2)B(3u) electronic state are considered. These effects are discussed in terms of B3LYP and CASSCF methods. It is shown that both absorption and excitation profiles discussed in the 1(2)B(2g) --> 1(2)B(3u) excitation region are in excellent agreement with those available from the experiment. The computations confirm D-2h symmetry of the TCNQ(-) molecule in its lowest energy 1(2)B(3u) doublet. On the other hand in at least one of two states 2(2)B(3u) or 1(2)A(u), the computations suggest that the symmetry of TCNQ monoanion is unstable being reduced from the D-2h to the C-2h, symmetry. (C) 2004 Elsevier BN. All rights reserved.