STILBENE ISOMERIZATION DYNAMICS ON MULTIDIMENSIONAL POTENTIAL-ENERGY SURFACE - MOLECULAR-DYNAMICS SIMULATION

The dynamics in the photoisomerization of isolated cis-stilbene, especially the dynamics leading to the intermediate twisted configuration is explored by molecular dynamics simulation. Comparison of the dynamics of the trans and cis isomers shows that for cis-stilbene the time required to reach the twisted configuration is an order of magnitude or two less than for trans-stilbene, due only to the specific steric interactions, and not to any difference in the potential functions or parameters. A barrier of between 510 and 640 cm(-1) along the torsional coordinate from the cis side is estimated for isolated molecule, accounting for a transition to the intermediate in approximately 300 fs.