Quantum dynamics analysis of transition-state spectrum for the SH + H2S -> H2S + SH reaction

摘要

We present the results of quantum wave packet calculations analyzing the experimental transition-state spectrum for the SH + H2S hydrogen transfer reaction based on photodetachment of the H(3)S(2)(-)anion. We used a reduced-dimensionality model in which four normal-mode coordinates were considered for the dynamics of the neutral transition state. The four-dimensional potential energy surfaces for the anionic and neutral states were constructed using four different levels of theory, namely, MP2, B3LYP, CAM-B3LYP, and LC-BLYP, with the aug-cc-pVDZ basis set. The spectrum calculated using the scaled MP2 potential energy surface was in reasonable agreement with the experimental spectrum. The present theoretical study confirms that the vibrational progression observed experimentally is associated with the antisymmetric motion of the transferred hydrogen atom. We also found that the S-S stretching motion plays an important role in the transition-state dynamics.