Spin–orbit corrected potential energy surface features for the I (2P3/2) + H2O → HI + OH forward and reverse reactions

Abstract

Using the CCSD(T) method with relativistic correlation consistent basis sets up to cc-pVQZ-PP, the entrance complex, transition state, and exit complex for the endothermic reaction I + H2O → HI + OH have been studied. The vibrational frequencies and the zero-point vibrational energies of the five stationary points for the title reaction are reported and compared with the limited available experimental results. Opposite to the valence isoelectronic F + H2O system, but similar to the Cl + H2O and Br + H2O reactions, the I + H2O reaction is endothermic, in this case by 46 kcal mol(-1). After the zero-point vibrational energy and spin-orbit coupling corrections, the endothermic reaction energy is predicted to be 48 kcal mol(-1), which agrees well with experimental values. For the reverse reaction HI + OH → I + H2O the transition state lies below the reactants, consistent with the experimental negative temperature dependence for the rate constants.

Features of the potential energy surface for the SiO + OH → SiO2+ H reaction: relationship to oxygen isotopic partitioning during gas phase SiO2formation

“…The CCSD(T) method with large basis sets has recently been used to study the potential energy surfaces of F + H 2 O, Cl + H 2 O, and I + H 2 O, [13][14][15] and those results are in good agreement with the limited available experimental ndings. In the present work, we use the same CCSD(T) method with correlation consistent basis sets up to cc-pV(Q+d)Z to study the stationary points on the potential energy surface for the SiO + OH / SiO 2 + H reaction.…”

Kinetics of the OH+HCl→H2O+Cl reaction: Rate determining roles of stereodynamics and roaming and of quantum tunneling

“…Figure , top panel, shows a schematic view of the potential energy surface profile for the four cases: it is reconstructed from data in Ref. [], where the main focus was actually on the inverse reactions. The reaction among hydroxyl radical with hydrogen iodine, hydrogen bromide and hydrogen chloride are highly exothermic, with Δ H 0 equal a − 47.9, −31.7, and − 16.1 Kcal/mol, respectively, while the reaction with hydrogen fluoride is endothermic (Δ H 0 =17.6 kcal/mol) .…”

“…Pictorial view of comparing schematically the stationary points on the potential energy surfaces for the OH + HX → H 2 O + X (X = Halogen), adapted from Ref. []. The influence of tunneling effect increases from HI to HF and that of sterodynamics increases in the opposite direction (see opposite arrows in the upper panel).…”

“…The anisotropic forces generated by electrostatic and dispersion interactions between reactants promote the formation of the wells in the entrance channels in the PES. However, differently from the entrance channel complex (HO‐‐‐HX), the origin of stability of the exit channel complex (X‐‐‐H 2 O) cannot be explained by electrostatic or dispersion interactions, since neither the geometry nor the energy encodes with this type of interactions. Ref.…”

Zero-point energy conservation in classical trajectory simulations: Application to H2CO

“…29,66 The method we propose is conceptually similar to that used by several authors to construct an effective potential for classical trajectories that incorporates spin-orbit coupling correction terms. [54][55][56]67,68 The harmonic ZPE of a molecular system is defined at stationary points on the PES as 69…”