Non-oscillatory flux correlation functions for efficient nonadiabatic rate theory

Area of Science:

• Quantum dynamics
• Chemical reaction theory
• Computational chemistry

Background:

• Simulating nonadiabatic processes is crucial for understanding complex chemical systems.
• Current trajectory-based methods struggle with accurate rate constant calculations, especially in the weak-coupling limit.
• The standard quantum flux correlation functions exhibit problematic oscillations in the weak-coupling regime.

Purpose of the Study:

• To develop an improved trajectory-based method for simulating nonadiabatic processes.
• To address the inherent sign problem in current methods for weak-coupling dynamics.
• To enable accurate calculation of rate constants across a broad spectrum of electronic coupling strengths.

Main Methods:

• Derivation of a modified flux correlation function using linear response theory.
• Trajectory simulations utilizing the new correlation function.
• Connecting the modified formalism to generalized quantum golden-rule transition-state theory and Marcus theory.

Main Results:

• The modified flux correlation function avoids oscillations in the weak-coupling regime.
• The new method provides accurate long-time limit results irrespective of coupling strength.
• The formalism establishes a link between transition-state dynamics and established theories like Marcus theory.

Conclusions:

• The developed modified flux correlation function offers a robust platform for simulating nonadiabatic dynamics.
• This advancement aids in developing more accurate nonadiabatic rate theories for complex systems.
• The method overcomes limitations of existing techniques, particularly in the challenging weak-coupling limit.