SPADE 1.0: A Simulation Package for Non-Adiabatic Dynamics in Extended Systems

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Chemical Physics

Background:

• Nonadiabatic molecular dynamics (NAMD) simulations are essential for understanding photochemical and photophysical processes.
• Traditional NAMD methods struggle with large, complex systems due to computationally intensive on-the-fly ab initio calculations and nonadiabatic coupling computations.

Purpose of the Study:

• Introduce a new software package, SPADE (Simulation Package for non-Adiabatic Dynamics in Extended systems).
• Address the limitations of existing surface hopping methods in NAMD simulations.
• Provide a flexible and efficient tool for simulating complex chemical dynamics.

Main Methods:

• SPADE allows users to define arbitrary quasi-diabatic Hamiltonians using parametrized functions.
• Incorporates advanced algorithms like global flux hopping probabilities and complex crossing/decoherence corrections.
• Enables efficient NAMD simulations without explicit calculation of nonadiabatic couplings.
• Modular design in Fortran allows for easy implementation of new methods.

Main Results:

• SPADE demonstrates efficient and reliable NAMD simulations for both model and atomistic systems.
• The software's flexibility in defining Hamiltonians and incorporating various algorithms is showcased.
• Successful simulation of representative models highlights SPADE's capabilities.

Conclusions:

• SPADE offers a powerful and flexible alternative for NAMD simulations, particularly for complex systems.
• The package overcomes key computational bottlenecks associated with traditional NAMD approaches.
• SPADE is a valuable tool for researchers investigating photochemical and photophysical processes.