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Conservation laws in coupled cluster dynamics at finite temperature
Ruojing Peng1, Alec F White1, Huanchen Zhai1
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
The Journal of Chemical Physics
|August 3, 2021
Summary
We developed a new method for simulating quantum systems at finite temperatures, ensuring conservation laws are upheld. This advances the study of non-equilibrium dynamics in materials and molecules.
Area of Science:
- Quantum Many-Body Physics
- Computational Chemistry
- Condensed Matter Physics
Background:
- Finite-temperature Keldysh non-equilibrium coupled cluster theory (Keldysh-CC) is a powerful tool for studying quantum systems out of equilibrium.
- Existing methods may face challenges in conserving fundamental physical laws during simulations.
- The development of accurate theoretical frameworks is crucial for understanding complex quantum phenomena.
Purpose of the Study:
- To extend the finite-temperature Keldysh non-equilibrium coupled cluster theory (Keldysh-CC) by incorporating a time-dependent orbital basis.
- To ensure the restoration of local and global conservation laws (Ehrenfest's theorem) for one-particle properties.
- To present and validate the time-dependent Keldysh orbital-optimized coupled cluster doubles method for finite-temperature dynamics.
Main Methods:
- Incorporation of a time-dependent orbital basis into the Keldysh-CC framework.
- Optimization of the orbital basis to minimize the action, thereby restoring conservation laws.
- Extension of the coupled cluster doubles method to finite temperatures using the time-dependent Keldysh contour.
- Application of the developed method to diverse non-equilibrium quantum systems.
Main Results:
- The time-dependent orbital basis successfully restores conservation laws (Ehrenfest's theorem) for one-particle properties.
- The method remains energy conserving for time-independent Hamiltonians.
- Numerical applications demonstrated the method's ability to handle complex non-equilibrium dynamics.
Conclusions:
- The developed time-dependent Keldysh orbital-optimized coupled cluster doubles method provides a robust framework for simulating non-equilibrium finite-temperature quantum dynamics.
- This advancement is crucial for accurate theoretical predictions in fields like materials science and quantum chemistry.
- The method's conservation properties offer enhanced reliability for studying driven quantum systems.
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