HELIUM DIMER POTENTIAL FROM SYMMETRY-ADAPTED PERTURBATION-THEORY

The intermolecular potential for the helium dimer has been computed us ing infinite-order symmetry-adapted perturbation theory and very large orbital and explicitly correlated basis sets. Our potential is signif icantly deeper than recent literature potentials, After adding the rel ativistic retardation correction, it accurately reproduces bulk proper ties of helium, the inclusion of retardation being essential for this agreement. Transport properties and virial coefficients are expected t o be accurate enough to calibrate measuring apparatus.