Symmetric Post-Transition-State Bifurcation Reactions with Berry Pseudo-Magnetic Fields

TL;DR

This paper explores how Berry pseudo-magnetic fields, induced by electronic degeneracy and spin-orbit coupling, can influence product selectivity in post-transition state bifurcation reactions by modifying nuclear dynamics.

Contribution

It introduces a dynamical model incorporating Berry forces and develops an analytic framework to predict their impact on reaction selectivity.

Findings

Berry force effects can alter product distribution in bifurcation reactions.

Dynamical simulations show noticeable changes in methoxy radical isomerization.

Analytic model links surface topology and Berry force magnitude to selectivity.

Abstract

We investigate how the Berry force (i.e. the pseudo-magnetic force operating on nuclei as induced by electronic degeneracy and spin-orbit coupling (SOC)) might modify a post-transition state bifurcation (PTSB) reaction path and affect product selectivity for situations when multiple products share the same transition state. To estimate the magnitude of this effect, Langevin dynamics are performed on a model system with a valley-ridge inflection (VRI) point in the presence of a magnetic field (that mimics the Berry curvature). We also develop an analytic model for such selectivity that depends on key parameters such as the surface topology, the magnitude of the Berry force, and the nuclear friction. Within this dynamical model, static electronic structure calculations (at the level of generalized Hartree-Fock with spin-orbit coupling (GHF+SOC) theory) suggest that electronic-spin induced Berry force effects may indeed lead to noticeable changes in methoxy radical isomerization.