A windowed mean trajectory approximation for condensed phase dynamics.

Area of Science:

• Chemical Physics
• Quantum Dynamics
• Computational Chemistry

Background:

• Accurate simulation of quantum dynamics in condensed phase systems is crucial for understanding chemical processes.
• Existing semiclassical methods often struggle with accuracy, particularly at low temperatures and for off-diagonal density matrix elements.

Purpose of the Study:

• To develop a novel semiclassical method for approximating the dynamical propagation of density matrices in condensed phase systems.
• To rigorously test the accuracy and robustness of the proposed method against established models and numerically exact solutions.

Main Methods:

• A trajectory-based quasi-classical method is proposed, building upon the optimized mean trajectory approximation.
• The method incorporates ideas from filtering trajectory methods for improved density matrix propagation.
• The approach is validated using multistate electronic models, spin-boson models, and the Fenna-Matthews-Olson complex.

Main Results:

• The new method demonstrates significant improvement or comparable performance to existing semiclassical methods for dissipative systems, especially at low temperatures.
• For scattering models, the method exhibits limitations similar to mean-field propagation schemes.
• Results show excellent agreement with the numerically exact hierarchical equations of motion across various parameter regimes.

Conclusions:

• The proposed trajectory-based quasi-classical method offers a robust and accurate approach for simulating quantum dynamics in condensed phase systems.
• The method shows particular promise for studying dissipative systems and provides a valuable tool for computational chemistry and chemical physics.