Real Space Triplets in Quantum Condensed Matter: Numerical Experiments Using Path Integrals, Closures, and Hard...

Area of Science:

• Quantum statistical mechanics
• Condensed matter physics

Background:

• Understanding the structure of quantum systems is crucial for predicting their properties.
• Quantum hard-sphere systems serve as fundamental models for studying phase transitions.

Purpose of the Study:

• To investigate real space triplet correlations in quantum hard-sphere systems.
• To compare structural features across fluid, face-centered cubic (FCC), and cI16 solid phases.
• To evaluate the performance of different closure approximations for structural analysis.

Main Methods:

• Path integral Monte Carlo simulations were employed to model the quantum hard-sphere system.
• Closure computations, including Kirkwood superposition, Jackson-Feenberg convolution, and their average (AV3), were utilized.
• Analysis focused on equilateral and isosceles features of path-integral centroid and instantaneous structures, complemented by pair structure calculations.

Main Results:

• The AV3 closure approximation demonstrated remarkable performance for both centroid and instantaneous correlations.
• Significant correspondences were found between fluid and FCC phase structures on the coexistence line.
• Conspicuous differences at pair and triplet levels were identified between FCC and cI16 solid phases at high densities.

Conclusions:

• The AV3 closure is highly effective for analyzing quantum hard-sphere systems.
• Structural similarities exist between fluid and FCC phases near coexistence.
• Distinct structural behaviors differentiate FCC and cI16 phases, providing valuable insights for low-temperature physics and materials science.