Linear polyene electronic structure: Relaxed and vertical excitation energies

Abstract

Simple 1-electron theories predict an ordering of linear polyene electronic states different from that observed. Explicit consideration of the effects of electron-electron interaction may be introduced to correct this defect. This results in a simple model for linear polyene electronic structure that reproduces all accurately measured singlet state excitation energies. Through Franck-Condon analysis of the vibrational development of the optical spectra the difference between electronic energies of excited states at the ground state equilibrium geometry and the electronic energies of these excited states at their minimum energy geometry (relaxation energy) can be determined. This is done for the polyene 1 1B u state for chains with 6 through 14 conjugated carbon atoms and for the 2 1Ag state for chains with 8 and 14 conjugated carbon atoms.