The electronic structures of the 1(1)B(2) and 2(1)A(1) excited electronic states of the 1,3-dicyanomethylene croconate dianion are studied in the framework of complete active space self-consistent field (CASSCF) and Becke's three-parameter hybrid method with a Lee-Yang-Parr correlation functional methods applied on the level aug-cc-pVDZ basis set. The CASSCF/aug-cc-pVDZ treatment provides the ground (1(1)A(1)) and the excited 1(1)B(2) and 2(1)A(1) states geometries, which are then used to evaluate the Franck-Condon parameters in the 1(1)B(2) and 2(1)A(1) states. The quality of the numerical results is verified on the bases of experimental near-resonance and resonance Raman data available in the vis-UV excitation region. The analysis is done in terms of the vibronic model, which treats the totally symmetric vibrations as displaced harmonic oscillators. Under the resonance with the 1(1)A(1)-->1(1)B(2) electronic transition, that somewhat simplified vibronic model leads to excellent agreement between the theoretical and empirical excitation profiles for the nu(2)=2234 cm(-1), nu(9)=911 cm(-1), nu(13)=376 cm(-1), and nu(14)=318 cm(-1) fundamentals. At preresonance with the 1(1)A(1)-->1(1)B(2) electronic excitation the agreement with the experimental Raman spectrum is reasonable but some discrepancies are noticed for the nu(4)=1620 cm(-1) and nu(5)=1546 cm(-1) fundamental lines. We argue that the observed discrepancies can be removed when mode-mixing (Duszynski) effects between nu(4) and nu(5) vibrations in the 1(1)B(2) state are taken into account. (C) 2003 American Institute of Physics.