Tunneling dynamics dictated by the multidimensional conical intersection seam in the πσ*-mediated photochemistry of heteroaromatic molecules

摘要

The πσ*-mediated photochemistry of heteroaromatic molecules has provoked the investigation of the conical intersection dynamics.The Bom-Oppenheimer approximation fails at the conical intersection where the S1(ππ*)and S2(πσ*)states cross.The nonadiabatic transitions are much influenced by the nuclear configuration of the reactive flux particularly in the curve-crossing region encountered along the reaction pathway.In this article,we focus on the tunneling dynamics of phenols and thiophenols.The O(S)-H bond cleavage occurs via tunneling through the barrier which is dynamically shaped by the upper-lying S/S2 conical intersection in terms of the couplings at the individual branching planes as well as along the(3N-8)dimensional seam coordinates.State-specific tunneling rates and their interpretation are given for phenol,substituted phenols,thiophenol,ortho-substituted thiophenols,and benzenediols including their 1:1 water clusters.The completely orthogonal modes to the tunneling coordinate are very critical in the dynamic shaping of the reaction barrier.