Full-Dimensional Reactive Potential Energy Surfaces for OCS$^+$ $\rightarrow$ CO+S$^+$ Dissociation: Ground and Excited States

TL;DR

This paper develops detailed potential energy surfaces for OCS$^+$ cation, covering ground and excited states, enabling accurate dynamical studies of its dissociation and photodissociation processes.

Contribution

It introduces high-level ab initio PESs for OCS$^+$ in multiple states using RKHS, validated by dissociation limits and trajectory simulations, advancing the understanding of its reactive dynamics.

Findings

PESs accurately reproduce measured dissociation limits.

Multiple minima and state-crossings identified on PESs.

Trajectory simulations confirm numerical stability and energy conservation.

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 \textit{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(X$^1\Sigma^+$)+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 selected 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 chem-ionization dynamics of OCS.