(4)He Thermophysical Properties: New Ab Initio Calculations.

Area of Science:

• Atomic Physics
• Quantum Mechanics
• Physical Chemistry

Background:

• Significant advancements in atomic physics since 2000 have reduced the uncertainty of helium-helium potentials.
• Previous calculations of helium-4 thermophysical properties relied on less precise potentials.

Purpose of the Study:

• To construct a new, highly accurate inter-atomic potential for helium-helium interactions (ϕ 07).
• To recalculate key thermophysical properties of helium-4 (second virial coefficient, viscosity, thermal conductivity) over a wide temperature range.
• To analyze the propagation of uncertainties from the potential and the Born-Oppenheimer approximation.

Main Methods:

• Utilized refined ab initio calculations for the helium-helium potential.
• Recalculated thermophysical properties using the new potential.
• Performed uncertainty propagation analysis.

Main Results:

• Developed a new inter-atomic potential, ϕ 07, with significantly reduced uncertainty.
• Generated updated values for the second virial coefficient, viscosity, and thermal conductivity of helium-4 from 1 K to 10,000 K.
• Quantified the impact of potential uncertainty and the Born-Oppenheimer approximation on thermophysical property calculations.

Conclusions:

• The new ϕ 07 potential provides a more accurate basis for calculating helium-4 thermophysical properties.
• The recalculated properties serve as reliable standards for experimental measurements.
• Understanding uncertainty propagation is crucial for accurate theoretical predictions.