Characteristic Rate of Unimolecular Isomerization in Molecules with Three Stable Isomer States

We have applied Gray-Zhao-Rice theory of the rate of unimolecular isomcrization to the molecular systems which support three stable isomer states A,B and A', represented by a linear Symmetric triple well potential. The major point of interest in the present study is searching for the possibility in the multistate theory to charaeterize the isomerization reaction by a single time scale. We find that the characteristic rate of isomcrization A→A' is featured by the time evolution of the state population of A'（t）. The characteristic time scale is dctermined from the maximum population of A’（t）. The decay rates and the characteristic rates of the isomerization for the three stable isomer systems are reported, and compared to those generated from the Reactive Island theory. We find that the Zhao-Rice version of the classical rate theory of isomerisation yields values of reaction rates in good agreement with the predictions from various other theories.