Improving the Accuracy of Quasiclassical Mapping Hamiltonian Methods by Treating the Window Function Width as an...

Area of Science:

• Computational chemistry
• Quantum dynamics
• Molecular simulation

Background:

• Mapping Hamiltonian methods are crucial for simulating electronically nonadiabatic molecular dynamics.
• These methods utilize quasiclassical approximations, treating various coordinates and momenta as classical-like phase-space variables.
• Different methods employ window functions with varying functional forms and treatments of window width.

Purpose of the Study:

• To investigate the impact of treating window width as an adjustable parameter within LSC-based methods.
• To compare the accuracy of LSC methods with adjustable window width to the SQC method.
• To evaluate the effectiveness of this adjustment on benchmark models.

Main Methods:

• Employed quasiclassical mapping Hamiltonian methods.
• Utilized window functions for sampling and calculating expectation values.
• Investigated linearized semiclassical (LSC) and symmetrical quasiclassical (SQC) approximations.
• Tested methods on spin-boson and Fenna-Matthews-Olson (FMO) complex models.

Main Results:

• Treating window width as an adjustable parameter in LSC methods significantly impacts accuracy.
• LSC methods with adjustable window width demonstrated accuracy comparable to SQC methods.
• The findings were consistent across both spin-boson and FMO benchmark models.

Conclusions:

• Adjustable window width is a key factor in improving the accuracy of LSC-based methods.
• This adjustment bridges the accuracy gap between LSC and SQC methods.
• The study provides a pathway for enhancing quasiclassical simulations of molecular dynamics.