Imaginary time correlations and the phaseless auxiliary field quantum Monte Carlo

Area of Science:

• Quantum many-body physics
• Computational quantum chemistry
• Advanced simulation techniques

Background:

• The phaseless Auxiliary Field Quantum Monte Carlo (AFQMC) method is a robust approach for determining ground state energies in many-fermion systems.
• Calculating imaginary time correlation functions is crucial for understanding system dynamics and properties.
• Existing methods may face limitations in accurately computing these correlation functions.

Purpose of the Study:

• To investigate and establish the capability of the phaseless AFQMC method for computing imaginary time correlation functions.
• To provide a detailed methodological description of this extended AFQMC application.
• To rigorously assess the accuracy of the phaseless AFQMC results for both static properties and imaginary time correlation functions.

Main Methods:

• Implementation of imaginary time correlation function calculations within the phaseless AFQMC framework.
• Systematic testing and validation using small, exactly solvable model systems.
• Comparison of phaseless AFQMC-derived static properties and correlation functions against precisely known exact values.

Main Results:

• Successful computation of imaginary time correlation functions using the phaseless AFQMC method.
• Demonstrated accuracy of the method for static properties, consistent with established benchmarks.
• High fidelity of calculated imaginary time correlation functions when compared to exact results for the tested systems.

Conclusions:

• The phaseless AFQMC method is a viable and accurate technique for calculating imaginary time correlation functions in many-fermion systems.
• This extension of AFQMC enhances its utility for studying both static and dynamic properties of quantum systems.
• The validated approach opens new avenues for high-accuracy simulations in quantum science and chemistry.