Open system dynamics using Gaussian-based multiconfigurational time-dependent Hartree wavefunctions: Application to...

Area of Science:

• Quantum mechanics
• Statistical mechanics
• Computational chemistry

Background:

• Modeling quantum dynamics of statistical mixtures is crucial for understanding complex systems.
• Existing methods face challenges in accurately describing dissipation and decoherence.

Purpose of the Study:

• To develop a variational approach for quantum dynamics of statistical mixtures.
• To incorporate dissipation and decoherence using nonstochastic open-system Schrödinger equations.
• To analyze quantum tunneling and thermalization in a model system.

Main Methods:

• Hybrid Gaussian-based Multiconfiguration Time-Dependent Hartree (G-MCTDH) wavefunctions for representing mixture states.
• The ρG-MCTDH method combined with open-system Schrödinger equations.
• Master equations (Lindblad and Caldeira-Leggett) for vibrational relaxation and thermalization.

Main Results:

• Demonstrated performance and convergence of the ρG-MCTDH approach.
• Illustrated quantum tunneling dynamics in a two-dimensional system.
• Visualized the transition from quantum tunneling to classical-limit distributions via flux analysis.

Conclusions:

• The ρG-MCTDH method provides an effective framework for studying quantum dynamics of statistical mixtures with dissipation and decoherence.
• The study successfully visualizes the quantum-to-classical transition driven by environmental interactions.