LAUSR

Abstract The reaction mechanism and kinetics have been studied to investigate the possible effect of water vapor on the CH 3 SH + H reaction. Based on the energy profile for the studied reactions obtained at CCSD(T)/aug-cc-pVTZ//MP2(full)/6–311++G (3df,3pd) levels of theory with ZPE correction, the formation of P1(CH 3 S + H 2 ) is predominant both in the absence and presence of water vapor. Due to the formation of hydrogen bond, the energies of transition states for reaction with water vapor are lower than those of naked reaction. Accordingly, in the presence of water vapor, the total rate constants computed by transition state theory are about 1–2 orders of magnitude larger than those of naked reaction at 249–605 K, which indicates that the involvement of water vapor would play an important role for the CH 3 SH + H reaction.