On the calculation of single-particle time correlation functions from Bose-Einstein centroid dynamics

Area of Science:

• Quantum mechanics
• Statistical mechanics
• Computational chemistry

Background:

• Calculating single-particle time correlation functions is crucial for understanding quantum systems.
• Existing methods often struggle with incorporating quantum statistical effects, particularly for anharmonic systems.

Purpose of the Study:

• To discuss the calculation of single-particle time correlation functions using Bose-Einstein centroid dynamics.
• To introduce a new quasidensity operator for calculating centroid forces in anharmonic systems.
• To enable the calculation of quantum exchange effects within centroid molecular dynamics.

Main Methods:

• Utilized a novel definition of the quasidensity operator to compute the centroid force.
• Employed the centroid molecular dynamics approximation for classical-like dynamics of phase-space centroid variables.
• Calculated single-particle time correlation functions, equivalent to the double-Kubo transform of exact quantum correlation functions.

Main Results:

• Achieved good agreement between Bose-Einstein centroid dynamics results and exact basis-set calculations.
• Demonstrated accuracy comparable to previous studies on center-of-mass correlation functions and Boltzmann statistics.
• Validated the capability of the method to handle quantum exchange effects in single-particle correlation functions.

Conclusions:

• Bose-Einstein centroid molecular dynamics is now a viable method for computing single-particle correlation functions.
• The approach effectively incorporates quantum statistical and exchange effects in anharmonic systems.
• This advancement expands the applicability of centroid dynamics to a broader range of quantum systems.