posted on 2020-03-06, 13:42authored byUlrich
K. Deiters, Richard J. Sadus
The ability of modern ab initio potentials to predict the thermophysical
properties of helium is investigated. A new interatomic potential
for helium is reported that is based on the latest available ab initio
data and that is much more computationally efficient than other ab
initio potentials, without sacrificing accuracy. The role of both
two-body and three-body interactions is evaluated using classical
Monte Carlo and molecular dynamics simulations. Data are reported
for the second virial coefficient, vapor–liquid equilibria,
acentric factor, compressibility factor, enthalpy, speed of sound,
and isobaric heat capacity. Three-body interactions have a minor influence
on the properties of helium with the exception of the estimated critical
properties. The influence of quantum particle behavior is relevant
at temperatures typically below 200 K. For example, the experimental
maximum in the isobaric heat capacities (along isobars) of helium
is not observed in the classical simulations and can be attributed
to quantum particle behavior. However, above this temperature, helium
behaves like a classical fluid and its thermodynamic properties can
be adequately predicted by determining only two-body interactions.