On the thermophysical and transport properties of 3 He and 4 He: A bubble interaction potential versus state of the art.

Three keynote thermophysical and transport properties of 3 He and 4 He, namely, the second virial coefficient, the shear viscosity, and the thermal conductivity, are reported for the "extended Dirac bubble potential" (EDbp), a novel model for He-He [M. Chrysos, J. Chem. Phys. 146, 024106 (2017)]. Comparisons with the experiment as well as with potentials with a proven track record and with the oversimplified Dbp are being made in the range 0.1-500 K to analyze the performance of the EDbp, which is shown here to emerge as a promising analytic model for He-He. A flowchart of how to treat the "buffer" in scattering cross section measurements is designed and conducted, offering a route to EDbp optimization. An impressive consistency with state-of-the-art calculations (which is just striking for such a simple analytic model) is found, essentially thanks to the performance of the phase-shift expression cotδl  = λkr0 ξl yl (kr0 )-yl (krc )λkr0 ξl jl (kr0 )-jl (krc ), ξl =jl (kr0 )yl (krc )-jl (krc )yl (kr0 ). A Multimedia view of δl (k,rc ) versus k and rc is part of the material presented in this article. Data for the "best" rc (k) is given as a supplementary material.