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Path integral density matrix dynamics: a method for calculating time-dependent properties in thermal adiabatic and
1Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom.
The Journal of Chemical Physics
|September 21, 2013
Summary
We present a new, formally exact method for calculating quantum time-correlation functions in thermal systems. This approach uses path integral simulations and Gaussian wavepacket dynamics for accurate quantum property calculations.
Area of Science:
- Quantum mechanics
- Computational chemistry
- Statistical mechanics
Background:
- Calculating time-dependent quantum properties in many-body thermal systems is computationally challenging.
- Existing methods often struggle with accuracy or efficiency for complex systems.
Purpose of the Study:
- To introduce a new, formally exact methodology for computing quantum time-correlation functions and time-dependent expectation values.
- To provide a versatile approach applicable to both adiabatic and non-adiabatic quantum systems.
Main Methods:
- Utilizes path integral simulations to sample the initial thermal density matrix.
- Employs a linear expansion of Gaussian wavepacket basis functions for real-time evolution.
- The wavepacket dynamics follow classical-like trajectories, enabling efficient computation.
Main Results:
- The method is demonstrated to be formally exact for time-dependent quantum properties.
- Validation on the spin Boson model shows excellent agreement with numerically exact results.
- The approach is adaptable to complex many-particle systems with arbitrary potentials.
Conclusions:
- The developed methodology offers a powerful and accurate tool for studying quantum dynamics in thermal systems.
- Future work will focus on approximations to enhance efficiency and accuracy for larger systems.
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