Nonadiabatic Ab Initio Molecular Dynamics with the Floating Occupation Molecular Orbital-Complete Active Space...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Direct nonadiabatic dynamics simulations are crucial for understanding photochemical processes.
• The complete active space self-consistent field (CASSCF) method is widely used but can be computationally demanding.
• Exploring efficient and stable alternatives is essential for advancing excited-state dynamics simulations.

Purpose of the Study:

• To evaluate the floating occupation molecular orbital complete active space configuration interaction (FOMO-CASCI) method as an alternative to CASSCF.
• To compare the performance of FOMO-CASCI and CASSCF in direct nonadiabatic dynamics simulations.
• To investigate the photodynamics of ethylene, methaniminium cation, and malonaldehyde using both methods.

Main Methods:

• Simulated photodynamics using direct nonadiabatic dynamics.
• Employed both FOMO-CASCI and CASSCF computational methods.
• Analyzed time evolution of electronic populations and reaction mechanisms.

Main Results:

• FOMO-CASCI and CASSCF generally yielded similar results for the simulated molecules.
• Observed dynamical differences were attributed to minor variations in potential energy surfaces.
• FOMO-CASCI demonstrated efficiency and stability in excited-state dynamics.

Conclusions:

• FOMO-CASCI is a promising and viable alternative to CASSCF for direct ab initio dynamics.
• The method's efficiency and stability make it suitable for excited-state simulations.
• Further application of FOMO-CASCI can advance the study of photochemical reactions.