Combining the mapping Hamiltonian linearized semiclassical approach with the generalized quantum master equation to...

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Physics

Background:

• The generalized quantum master equation (GQME) is essential for simulating nonadiabatic molecular dynamics.
• Nuclear-electron coupling is captured by a memory kernel superoperator within the GQME framework.

Purpose of the Study:

• To evaluate two novel procedures for calculating the GQME memory kernel using projection-free inputs.
• To assess the accuracy and feasibility of these methods, specifically the mapping Hamiltonian (MH) and linearized semiclassical (LSC) approximation combination.
• To compare the performance of MH/LSC methods against the Ehrenfest method for memory kernel calculation.

Main Methods:

• Developing and applying two projection-free procedures to compute the memory kernel for the GQME.
• Utilizing the mapping Hamiltonian (MH) approach combined with the linearized semiclassical (LSC) approximation.
• Testing the methods on the well-established spin-boson model.

Main Results:

• Direct application of LSC-based procedures for electronic dynamics simulation yielded inaccurate and divergent results over time.
• Restricting the LSC-based procedures to memory kernel calculation resulted in accurate electronic dynamics.
• MH/LSC-derived memory kernels exhibited improved long-time behavior and greater accuracy compared to the Ehrenfest method.

Conclusions:

• The proposed MH/LSC methods for calculating the GQME memory kernel provide an accurate and robust approach for nonadiabatic molecular dynamics.
• These methods offer a significant improvement over direct simulation using LSC approximations and are superior to the Ehrenfest method for long-time dynamics.