Semiclassical Monte Carlo: a first principles approach to non-adiabatic molecular dynamics

Area of Science:

• Quantum chemistry
• Theoretical chemistry
• Computational chemistry

Background:

• Modeling photophysical and photochemical reactions in large molecular systems is challenging.
• Existing methods for non-adiabatic dynamics are often computationally expensive or rely on approximations.
• Accurate simulation requires incorporating electronic state transitions and quantum coherence effects.

Purpose of the Study:

• To present a novel algorithm for simulating non-adiabatic dynamics in extended molecular systems.
• To provide a cost-effective and systematically improvable method for quantum chemistry.
• To achieve excellent agreement with exact quantum mechanical results.

Main Methods:

• Monte Carlo sampling of the semiclassical time-dependent wavefunction.
• Surface hopping dynamics simulation.
• Post-processing step for enhanced accuracy.

Main Results:

• The algorithm demonstrates excellent agreement with exact quantum mechanical solutions for scattering problems.
• Wavefunction convergence is influenced by complex-valued phase factors, non-adiabatic coupling region size, and sampling function choice.
• The method requires minimal input from quantum chemistry calculations and is computationally efficient.

Conclusions:

• The developed algorithm is a promising tool for simulating complex molecular dynamics in large systems.
• The findings provide insights into the method's applicability and suggest avenues for future improvements.
• This approach bridges the gap between accuracy and computational cost in quantum dynamics simulations.