Optimizing hierarchical equations of motion for quantum dissipation and quantifying quantum bath effects on quantum...

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Physics

Background:

• Quantum dissipation describes energy loss in quantum systems interacting with their environment.
• Accurate modeling of quantum dissipation is crucial for understanding chemical reactions and material properties.
• Existing methods often struggle with complex environments, such as multiple Brownian oscillators.

Purpose of the Study:

• To present an optimized hierarchical equations of motion (HEOM) theory for quantum dissipation.
• To develop a mechanistic study on a model donor-bridge-acceptor system.
• To quantify the quantum nature of bath influence and analyze localization-delocalization transitions.

Main Methods:

• Optimized HEOM theory utilizing memory-frequency decomposition for bath characterization.
• Universal pre-screening search for optimal hierarchy construction, including Padé spectrum decomposition.
• Development of reduced system entropy and state-resolved interference measures for system-environment coherence.

Main Results:

• Demonstrated general achievability of optimal hierarchy construction via pre-screening.
• Identified optimal HEOM schemes for Drude dissipation and specific Brownian oscillator environments.
• Quantified quantum effects on system dynamics, revealing a temperature-dependent localization-delocalization transition.

Conclusions:

• The optimized HEOM theory provides an efficient and accurate approach for quantum dissipation studies.
• The proposed measures effectively quantify system-environment coherence and quantum effects.
• The study highlights the critical role of temperature in controlling quantum system behavior and phase transitions.