Unlocking the Double Bond in Protonated Schiff Bases by Coherent Superposition of S1 and S2

The primary event occurring during the E-to-Z photoisomerization reaction of retinal protonated Schiff base (rPSB) is single-to-double bond inversion. In this work we examine the nuclear dynamics that occurs when the initial excited state is a superposition of the S-1 and S-2 electronic excited states that might be created in a laser experiment. The nuclear dynamics is dominated by double bond inversion that is parallel to the derivative coupling vector of S-1 and S-2. Thus, the molecule behaves as if it were at a conical intersection even if the states are nondegenerate.

Automated summary

The study examines the nuclear dynamics during the photoisomerization reaction, focusing on double bond inversion. The molecule exhibits characteristics similar to a conical intersection during the process of double bond inversion, even when the states are nondegenerate.