ABINITIO STUDY OF THE CIS-TRANS PHOTOISOMERIZATION OF STILBENE

The molecular energies of the ground and lowest excited σσ* states for the cis and trans isomers of stilbene and for the twisted geometry of the molecule have been evaluated by the SCF method followed by configuration mixing. The orbital basis is a minimal basis of STO/3G orbitals and the CI includes all relevant second-order interactions of the ground and lowest excited configurations. Two-term Fourier interpolations of the computed energies have provided potential energy curves along the coordinate of internal rotation. The potential curves support the adiabatic mechanism for the trans-cis thermal conversion in the ground state and for the sensitized photoconversion in the lowest triplet state and a nonadiabatic mechanism for the direct photoisomerization in the lowest excited singlet state. Copyright © 1979, American Chemical Society. All rights reserved.