Mechanism and electronic transition in the Cl + O ₃ → ClO + O ₂ reaction: On the fly dynamics simulations with multi-reference potentials

A mechanistic study of the reaction Cl+O ₃→ClO+O ₂ at the high level of multi-reference DET-MRPT2 theory for both the static reaction path and the dynamics is presented. It is found that a spin-flip takes place along the computed dynamical path, a point neglected in previous studies. The time scale of the spin-flip is estimated from the dynamics. The algorithmic improvements that make possible the high-level multi-reference dynamics simulation are briefly discussed.