Results are presented from ab initio calculations on the ground and two low-lying excited states of the hexatriene radical cation in a variety of stable conformations of the electronic ground state of the molecule. We have performed Hartree-Fock geometry optimizations using the STO-3G and 6-31g basis sets and have performed vibrational analyses for all stable conformers in the 6-31G basis. In addition, we have performed geometry optimizations in both basis sets using CASSCF wave functions where the five π electrons are correlated. No new geometrical information is obtained at this level of treatment. Excitation energies to the two lowest-lying doublet π excited states for the six stable ground-state geometries were also calculated using CASSCF wave functions. These excitation energies are compared with previous experimental assignments of observed transitions in photolytically generated hexatriene radical cations.
© 1992 American Chemical Society
Cave, R.J.; Johnson, J. “A CASSCF study of various rotamers of the hexatriene radical cation,” J. Phys. Chem. 1992, 96, 5332-5336. doi: 10.1021/j100192a029