Ab initio CI study on electronically excited stilbene

Ab initio configuration interaction calculations have been performed to examine the electronic structure of trans- and cis-stilbene. The optimized structure of trans-stilbene in S-0 is characterized as a molecule in which phenyl groups are connected with the ethylenic part through normal C-C single bonds but not that in which the rr-conjugated system is wholly delocalized over a molecule. The low-lying excited states, S-1, S-2, and S-3 states of the trans-form as well as the cis-one at the equilibrium geometry are mainly derived from pi-pi* single excitations. (C) 1999 Elsevier Science B.V. All rights reserved.