Symmetric Post-Transition State Bifurcation Reactions with Berry Pseudomagnetic Fields

Area of Science:

• Chemical dynamics
• Quantum chemistry
• Reaction mechanisms

Background:

• The Berry force, arising from electronic degeneracy and spin-orbit coupling (SOC), is a pseudomagnetic force acting on nuclei.
• Post-transition state bifurcation (PTSB) reactions can lead to multiple products from a single transition state.
• Understanding factors influencing product selectivity in such reactions is crucial for chemical synthesis.

Purpose of the Study:

• To investigate the influence of the Berry force on post-transition state bifurcation (PTSB) reaction paths.
• To determine how the Berry force affects product selectivity when multiple products share a common transition state.
• To quantify the impact of Berry force effects on methoxy radical isomerization.

Main Methods:

• Langevin dynamics simulations were performed on a model system featuring a valley-ridge inflection (VRI) point.
• A magnetic field was used to mimic the Berry curvature in the simulations.
• An analytic model was developed to describe selectivity based on surface topology, Berry force magnitude, and nuclear friction.
• Static electronic structure calculations using generalized Hartree-Fock with spin-orbit coupling (GHF+SOC) theory were employed.

Main Results:

• The Berry force, induced by electronic spin, can significantly alter reaction pathways.
• Product selectivity in reactions with shared transition states can be modified by these Berry force effects.
• Simulations suggest noticeable changes in methoxy radical isomerization due to electronic spin-induced Berry forces.

Conclusions:

• The Berry force is a relevant factor in determining chemical reaction outcomes and product selectivity.
• The developed analytic and dynamical models provide a framework for studying these effects.
• Further investigation into Berry force contributions in chemical reactions is warranted.