Trajectory surface hopping vs. quantum scattering calculations on D⁺ + H₂ and H + H₂⁺ reactions using ab initio surfaces and couplings

Abstract

We employ trajectory surface hopping (TSH) formalism to compute cross-sections or/and rate constants of D⁺ + H₂ (v = 0,j = 0) and H + H₂⁺ (v = 0, j = 0) reactions initiating from ground and first excited electronic state of H₃⁺, respectively. While solving Hamilton’s equations over adiabatic potential energy surfaces (PESs), switching probabilities are calculated by ab initio nonadiabatic coupling terms for the first time. During hopping, momenta are adjusted to fulfil total energy conservation, where a scaling factor is introduced to explore the conservation of linear momentum. For non-charge transfer process, quasi-classical cross-sections match well with quantum results obtained from diabatic PESs of H₃⁺, and experimental findings, but deviations are observed at the energy domain of conical intersection driven hopping for charge-transfer processes. Calculated results indicate the origin of limitations of TSH algorithm as well as depict computational advantage with respect to quantum dynamics.