Mechanism and electronic transition in the 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.