Electronic dephasing of polyatomic molecules interacting with mixed quantum-classical media

Area of Science:

• Quantum dynamics
• Statistical mechanics
• Computational chemistry

Background:

• Traditional semiclassical methods often exhibit limitations in accuracy and efficiency.
• Modeling interactions between quantum subsystems and classical environments is crucial for understanding molecular dynamics.

Purpose of the Study:

• To develop an expedient and efficient treatment for multimode quantum subsystems interacting with a classical environment.
• To introduce a new mixed quantum-classical dynamics approach based on non-Newtonian mechanics.

Main Methods:

• Utilized a unique time evolution of the coupling term governed by statistical mechanics rules.
• Employed matrix mechanics with LU decomposition and singular value decomposition (SVD) for diagonalization.
• Applied a multidimensional coherent-state approach for quantum subsystem time evolution.

Main Results:

• Accurate pure electronic dephasing in multimode molecular systems was achieved, eliminating line shape asymmetry.
• The model successfully handles various vibrational modes (slow, fast, or both) using different spectral densities.
• Derived closed-form expressions for optical electronic transition dipole moment time correlation functions.

Conclusions:

• The developed mixed quantum-classical dynamics approach is novel and offers superior advantages over existing methods.
• The method provides accurate simulations of thermal broadening, temporal decay, and pure dephasing.
• This work paves the way for more efficient and accurate studies of complex molecular systems.