Reaction dynamics for the Cl(${}^2$P) + XCl $\to$ XCl + Cl(${}^2$P) (X = H, D, Mu) reaction on a high-fidelity ground state potential energy surface

Abstract

Globally accurate full-dimensional ground state potential energy surface (PES) for the Cl(${}^2$P) + XCl $\to$ HCl + Cl(${}^2$P) reaction, a prototypical heavy-light-heavy abstract reaction, is developed using permutation invariant polynomial neural network (PIP-NN) method and embedded atom neural network (EANN) method, with the corresponding total root mean square error (RMSE) being only 0.043 and 0.056 kcal/mol, respectively. The saddle point of this reaction system is found to be nonlinear. A full-dimensional approximate quantum mechanical method, ring-polymer molecular dynamics (RPMD) with Cayley propagator, is employed to calculate the thermal rate coefficients and kinetic isotopic effects of title reactions Cl(${}^2$P) + XCl $\to$ XCl + Cl(${}^2$P) (X = H, D, Mu) on both new PESs. The results reproduce the experimental results at high temperatures perfectly, but with moderate accuracy at lower temperatures. The similar kinetic behavior is supported by quantum dynamics using wave packet calculations as well.