PRECISE PARISER-PARR-POPLE MOLECULAR-ORBITAL CALCULATIONS USING NEW-GAMMA - A NOVEL GUIDING PRINCIPLE FOR THE DESIGN OF FUNCTIONAL MATERIALS

For precise Pariser-Parr-Pople molecular orbital (PPP MO) calculations , the values of the spectrochemical softness parameter k of a new two- center electron repulsion integral new-gamma were evaluated based on a n appropriate partial structure of polycyclic aromatic hydrocarbons (P AHs). The spectroactive aromatic sextet resonance system (ASRS) was de fined as a spectroactive partial structure of a molecule. The calculat ed excitation energies of the p-band of PAHs accurately reproduced the observed ones.