Full-Dimensional Reactive Potential Energy Surfaces of OCS+ for S+ Dissociation: Ground and Excited States

Abstract Full-dimensional reactive potential energy surfaces (PESs) for the OCS+ cation are constructed to describe S+ loss in the electronic ground state and seven low-lying electronically excited states. High-level ab initio reference energies were computed at the MRCI+Q/aug-cc-pVTZ level and were used to generate PESs employing reproducing kernel Hilbert space representations (RKHS). The PESs accurately reproduce the measured dissociation limits to CO(X1Σ+) + S+ in different electronic states. The topology of the PESs reveals multiple linear and T-shaped minima, pronounced angular anisotropy, and state-crossing manifolds. Exploratory quasi-classical trajectory simulations on all PESs confirm numerical stability and energy conservation, illustrating the suitability of the surfaces for dynamical applications. The present work represents the most comprehensive characterization to date of the lowest PESs of OCS+ and provides a reliable foundation for future studies of the photodissociation of OCS+ and the chemi-ionization dynamics of OCS.