Precise PPP molecular orbital calculations of excitation energies of polycyclic aromatic hydrocarbons. Part 5 Spectroactive portion of fluoranthene derivatives

For Pariser¯Parr¯Pople molecular orbital (PPP MO) calculations of the p-band of fluoranthene derivatives, the values of the spectrochemical softness (SCS) parameter k in a novel two centre electron repulsion integral new-gamma were evaluated based on the spectroactive portion (SP) of a molecular framework. The SP was determined by the character of MO calculated by the HMO method with reference to the structural analysis by ab initio MO calculations with 6-31G* level. The calculated excitation energies of the p-band of fluoranthene derivatives using the new-gamma including k values based on the SP reproduced accurately the observed ones.