Validating and implementing modified Filinov phase filtration in semiclassical dynamics

Area of Science:

• Quantum Chemistry
• Computational Physics
• Chemical Dynamics

Background:

• Semiclassical (SC) methods approximate quantum mechanics for complex systems.
• Real-time quantum correlation functions are crucial for understanding chemical dynamics.
• Previous applications of modified Filinov filtration (MFF) in SC dynamics showed limited utility.

Purpose of the Study:

• To evaluate the effectiveness of the MFF scheme in conjunction with SC dynamics for calculating quantum correlation functions.
• To introduce a more computationally efficient formulation of the Mixed Quantum-Classical Initial Value Representation (MQC-IVR).

Main Methods:

• The study employed the Mixed Quantum-Classical Initial Value Representation (MQC-IVR) method.
• The modified Filinov filtration (MFF) scheme was applied to control the SC integrand's phase.
• Analysis of trajectory phase and amplitude contributions to the correlation function was performed.
• A novel MQC-IVR formulation was developed to improve computational scaling.

Main Results:

• The MFF scheme effectively reduces noise in SC correlation functions by damping amplitudes in highly oscillatory phase regions.
• This noise reduction by MFF enhances computational efficiency while maintaining accuracy.
• The new MQC-IVR formulation exhibits linear scaling with simulation length, a significant improvement over previous quadratic scaling.

Conclusions:

• The MFF scheme is highly effective for calculating real-time quantum correlation functions within the MQC-IVR framework.
• The developed MQC-IVR formulation offers substantial computational advantages for simulating complex quantum systems.