Direct Computation of Influence Functional Coefficients from Numerical Correlation Functions.

Area of Science:

• Quantum dynamics simulation
• Condensed matter physics
• Theoretical chemistry

Background:

• Influence functional methods are key for simulating quantum systems in harmonic baths.
• Current methods often rely on spectral density calculations, which can be complex.
• Parametrization allows these methods to model diverse environments and chemical processes.

Purpose of the Study:

• To develop a direct procedure for calculating discretized influence functional coefficients.
• To circumvent the need for spectral density computation via Fourier inversion.
• To offer an efficient and accurate alternative for quantum dynamics simulations.

Main Methods:

• Utilized the classical approximation to the time correlation function.
• Calculated influence functional coefficients directly from the correlation function.
• Leveraged data typically available from molecular dynamics simulations.

Main Results:

• The direct procedure yields results as accurate as spectral density methods when data is precise.
• The direct procedure shows improved accuracy in the presence of statistical noise.
• The method is computationally efficient and straightforward to implement.

Conclusions:

• The developed direct procedure provides a robust and efficient alternative for influence functional calculations.
• This method simplifies the simulation of quantum systems in harmonic baths.
• It is particularly advantageous for systems with noisy time correlation functions.