Classical molecular dynamics simulation of electronically non-adiabatic processes.

Area of Science:

• Computational Chemistry
• Molecular Dynamics
• Quantum Mechanics

Background:

• Classical molecular dynamics (MD) is widely used for simulating molecular systems on single potential energy surfaces (PES).
• Simulating electronically non-adiabatic processes, involving transitions between electronic states, remains a challenge for standard MD methods.
• Accurate simulation of large chemical systems requires efficient methods that can handle complex potential energy surfaces.

Purpose of the Study:

• To review recent developments in extending classical MD for electronically non-adiabatic processes.
• To present a unified approach treating nuclear and electronic degrees of freedom classically.
• To introduce the symmetrical quasi-classical (SQC) windowing model for electronic state quantization.

Main Methods:

• Extension of standard classical molecular dynamics (MD).
• Symmetrical quasi-classical (SQC) windowing model for electronic state quantization.
• Equivalent classical treatment of nuclear and electronic degrees of freedom.

Main Results:

• The SQC approach successfully treats electronically non-adiabatic processes.
• Accurate description of strong and weak electronic state coupling regimes.
• Accurate modeling of coherence and de-coherence effects in electronic degrees of freedom.

Conclusions:

• The reviewed approach offers a computationally feasible method for simulating non-adiabatic dynamics.
• Recent advancements include a superior SQC model variation and an extension for full electronic density matrix calculation.
• This method retains MD simplicity while enabling the study of complex electronic transitions.