Dynamics on potential energy surfaces with a conical intersection: Adiabatic, intermediate, and diabatic behavior
Abstract
The nuclear dynamics on potential energy surfaces which are strongly vibronically coupled through a conical intersection is investigated by exact (numerical) integration of the timedependent Schrödinger equation. Results for realistic model systems including three nuclear degrees of freedom are presented: C_{2}H^{+}_{4}, pyrazine and NO_{2}. It was found previously for C_{2}H^{+}_{4} that the wave packet moves after an initial decay mainly on the lower adiabatic surface. This observation could be confirmed also for pyrazine and NO_{2}. By varying the coupling strength λ also other types of behavior could be identified. A transition from adiabatic via intermediate to a diabatic nature of the system dynamics is found upon decreasing λ. Population of diabatic and adiabatic states in the long time limit are calculated by classical phasespace statistics. Analytic relations between the population of the diabatic states and the dynamical observables, coordinates and momenta, are derived. They allow for a deeper understanding of their long time limits.
 Publication:

Journal of Chemical Physics
 Pub Date:
 August 1990
 DOI:
 10.1063/1.459094
 Bibcode:
 1990JChPh..93.1658M
 Keywords:

 Adiabatic Conditions;
 Coupling;
 Dynamic Models;
 Perturbation Theory;
 Potential Energy;
 Schroedinger Equation;
 BornOppenheimer Approximation;
 Degrees Of Freedom;
 JahnTeller Effect;
 Nitrogen Dioxide;
 Population Theory;
 Statistical Mechanics;
 Vibration Mode;
 Atomic and Molecular Physics