VERTICAL EXCITATION-ENERGY TO THE LOWEST 1-PI-PI-STAR STATE OF ACROLEIN

In acrolein the use of orthogonal orbital SCF procedures on the lowest 1ππ* state results in a configuration which has a low energy but a high overlap with the ground-state wave function. Variationally correct nonorthogonal SCF procedures give a much higher energy estimate for this state. Configuration interaction calculations with the correct SCF orbitals in a basis set without Rydberg orbitals gives 7.52 eV for the best estimate of the excitation energy compared with the observed value of 6.5 eV. © 1979, American Chemical Society. All rights reserved.