Ab initiopotential energy curve for the helium atom pair and thermophysical properties of dilute helium gas. I. Helium–helium interatomic potential

Ab Initio Values of the Thermophysical Properties of Helium as Standards

Recent quantum mechanical calculations of the interaction energy of pairs of helium atoms are accurate and some include reliable estimates of their uncertainty. We combined these ab initio results with earlier published results to obtain a helium-helium interatomic potential that includes relativistic retardation effects over all ranges of interaction. From this potential, we calculated the the...

Ionization potential of the helium atom.

The ground-state ionization potential of the He4 atom is found to be 5 945 204 223 (42) MHz. Along with lower-order contributions, this result includes all effects of relative order alpha4, alpha(3)m(e)/m(alpha), and alpha(5)ln(2)alpha. Effective operators derived in dimensionally regularized nonrelativistic quantum electrodynamics are employed. The average values of these operators are evaluat...

Electron pair properties for the helium atom from explicitly correlated wave functions

Starting from a compact and accurate explicitly correlated wave function a systematic study of two-body properties in both position and momentum space has been performed for the He atom. A systematic comparison with the values obtained from both a multi-configuration Hartree–Fock and a Hylleraas (when available) wave function is performed. The wave function and the different expectation values ...

Semiclassical theory of helium atom

The Structure of the Helium Atom.