An Excitation Strategy for the Initial Condition Generation for Surface Hopping Trajectories Using Electron-Only...

Area of Science:

• Computational chemistry
• Photochemistry
• Molecular dynamics

Background:

• Nonadiabatic dynamics simulations are crucial for understanding photoinduced molecular phenomena.
• Current methods often use simplified models for photoexcitation, neglecting laser pulse details.
• Accurate modeling of laser-matter interactions is essential for reliable simulation outcomes.

Purpose of the Study:

• To develop a computationally efficient and accurate excitation scheme for trajectory surface hopping simulations.
• To incorporate explicit laser pulse characteristics (spatial, temporal, spectral) into simulation initial conditions.
• To provide a practical tool for researchers studying photoinduced processes.

Main Methods:

• The "electron-only explicit" (EOE) excitation scheme is proposed.
• It involves solving the time-dependent electronic Schrödinger equation with explicit laser pulse interaction.
• Initial electronic states for surface hopping are stochastically selected based on time-dependent electronic populations.
• Renormalization ensures efficient excitation, even in the weak-field regime.

Main Results:

• The EOE scheme provides accurate initial conditions for nonadiabatic dynamics simulations.
• Simulations of sodium iodide and 6-cyanobenzquinuclidine demonstrate the scheme's validity.
• The method is computationally inexpensive compared to full quantum dynamics.

Conclusions:

• The EOE scheme offers a significant improvement over approximate excitation methods.
• It enables more realistic modeling of photoexcitation in molecular dynamics.
• The scheme is integrated into the SHARC 4 dynamics package for broader accessibility.