GENERALIZED DIABATIC STUDY OF ETHYLENE “ISOMERISM“

The generalized electronic diabatic (GED) approach is used to study a cis-trans isomerization process. At variance with standard Born-Oppenheimer approach, where a unique adiabatic potential energy function depending of a dihedral angle connects both isomers, a configuration interaction model permits describing isomerization process with four diabatic electronic states. These GED states form a minimal CI space; each state conserves local symmetry properties along a properly defined reaction coordinate. The diabatic states diagonalize the Coulomb Hamiltonian. The state mixing obtains via kinematic couplings, electron-phonon and spin-orbit operators. The process is mapped to a full quantum mechanical linear superposition of diabatic states.