Ring polymer molecular dynamics with surface hopping.

Area of Science:

• Chemical Physics
• Computational Chemistry
• Quantum Dynamics

Background:

• Calculating chemical reaction rates accurately is crucial for understanding chemical processes.
• Nonadiabatic effects and quantum tunneling significantly influence reaction dynamics, posing challenges for classical molecular dynamics methods.

Purpose of the Study:

• To develop a new computational method combining ring polymer molecular dynamics with surface-hopping to calculate chemical rate constants.
• To incorporate nonadiabatic effects and quantum tunneling into molecular dynamics simulations of chemical reactions.

Main Methods:

• Formulated two approximate ring polymer electronic Hamiltonians.
• Solved the time-dependent Schrödinger equation for electronic amplitudes self-consistently with ring polymer equations of motion.
• Employed the fewest-switches surface-hopping criterion for transitions between electronic states.

Main Results:

• The proposed method accurately reproduces the tunneling contribution to reaction rates.
• It correctly predicts the distribution of reactants between electronic states in a model system.
• The method allows for the evaluation of total rate coefficients and electronic state-selected contributions.

Conclusions:

• The ring polymer molecular dynamics with surface-hopping is a promising approach for accurate calculation of chemical rate constants in nonadiabatic systems.
• This method provides a robust framework for studying complex chemical reactions involving quantum effects.