THE USE OF FRAGAS POTENTIAL WITH AM1 ATOMIC POINT CHARGES IN THE EVALUATION OF SPECTRAL SHIFTS - APPLICATION TO TICT MOLECULES

Fraga potential calculations with atomic point charges and geometrical parameters calculated from AM1 calculations have been used to calcula te spectral shifts upon electronic excitation in twisted intramolecula r charge transfer (TICT) systems due to intermolecular interactions. C hanges of atomic polarizabilities have also been taken into account. P resent calculations deal with absorption transitions of the p-N, N-dim ethylaminobenzonitrile (DMABN) surrounded by methane, water, acetone, or acetonitrile solvent molecules. The methodology permits us to evalu ate the influence of the solvent molecule on DMABN dimethylamino motio ns and to find the most stable conformation of a cluster configuration which can lead to a blue or red shift. The results have been compared with the experimental work of Warren et al.(7) and confirm their anal ysis. (C) 1994 by John Wiley and Sons, Inc.