High-level analytical potential-energy-surface-based dynamics of the OH− + CH3CH2Cl SN2 and E2 reactions in full (24) dimensions

We develop a coupled-cluster full-dimensional global potential energy surface (PES) for the OH− + CH3CH2Cl reactive system, using the ROBOSURFER program package, which automatically samples configurations along PES-based trajectories as well as performs ab initio computations with MOLPRO and fitting with the monomial symmetrization approach. The analytical PES accurately describes both the bimolecular nucleophilic substitution (SN2) and elimination (E2) channels leading to the Cl− + CH3CH2OH and Cl− + H2O + C2H4 products, respectively, and allows efficient quasi-classical trajectory (QCT) simulations. QCT computations on the new PES provide accurate statistically-converged integral and differential cross sections for the OH− + CH3CH2Cl reaction, revealing the competing dynamics and mechanisms of the SN2 and E2 (anti, syn, β−α transfer) channels as well as various additional pathways leading to induced inversion of the CH3CH2Cl reactant, H-exchange between the reactants, H2O⋯Cl− complex formation, and H2O + CH3CHCl products via proton abstraction.