Isomerization Through Conical Intersections

B. G. Levine and T. J. Martinez

The standard model for photoinduced cis-trans isomerization about carbon double bonds is framed in terms of two electronic states and a one-dimensional reaction coordinate. We review recent work which suggests that a minimal picture of the reaction mechanism requires consideration of at least two molecular coordinates and three electronic states. The role of conical intersections and charge transfer in the photoisomerization mechanism is emphasized.