Surface hopping with nuclear quantum effects through path-integral coarse graining

Area of Science:

• Chemical Physics
• Quantum Dynamics
• Computational Chemistry

Background:

• Nuclear quantum effects (NQEs), including tunneling and zero-point energy, are vital for accurately describing nonadiabatic molecular dynamics.
• Existing methods often face computational challenges when incorporating these effects.

Purpose of the Study:

• To develop a computationally efficient and robust scheme for modeling nonadiabatic dynamics with NQEs.
• To accurately predict reaction rates and correlation functions in systems exhibiting quantum phenomena.

Main Methods:

• A novel mixed quantum-classical approach combining centroid molecular dynamics with fewest-switches surface hopping (FSSH) is proposed, termed centroid-surface hopping.
• Path-integral coarse-graining is employed to mitigate computational costs associated with path-integral simulations.
• The method is validated against exact quantum mechanical calculations on two-state, one-dimensional model systems.

Main Results:

• The centroid-surface hopping method accurately predicts reaction rates and correlation functions across various regimes, including deep tunneling.
• Computational efficiency comparable to classical FSSH is achieved.
• Quantitative agreement with exact quantum mechanical results is demonstrated for all tested parameter sets.

Conclusions:

• The developed method provides an efficient and accurate means to incorporate NQEs in nonadiabatic dynamics.
• This advancement facilitates future modeling of complex chemical reactions and processes involving quantum effects.
• The approach shows promise for broader applications in computational chemistry and chemical physics.