The visible-light absorption and emission excitation energies of PM567 dye have been studied with different ab initio methods (TDHF, CIS, MP2, MP3 and CISD). The results show that its visible-light spectra are mainly due to a transition between the HOMO to the LUMO, with the CISD size consistency corrections values being the most accurate respect to the experimental data. In order to minimize the computational cost of the highly correlated methods, the range of orbital energies that must be included in correlation correction to carry out a complete description of each method was also studied. This range was fixed to 34 eV for the occupied and virtual orbital energies in the case of MP3 and CISD methods. (C) 2003 Elsevier Science B.V. All rights reserved.