Ab InitioCalculation of the Helium-HeliumΣg+1Potential at Intermediate and Large Separations

Abstract

A five-configuration wave function computed by multiconfiguration self-consistent field techniques has yielded a well depth $\frac{\epsilon }{k}=10.48\mathrm{}$°K at $r_m=5.659\mathrm{}$ bohrs and a potential zero $\sigma =5.037\mathrm{}$ bohrs for the interaction of ground-state He atoms. Improvement of the basis set yields, at $R=5.60\mathrm{}$, a potential $U\left(R\right)=11.38\mathrm{}$°K. It is suggested that calculations in the vein of the present approximation should converge to a well depth of close to 12°K. The long-range behavior of our potential is unexpectedly close to that commonly accepted for He-He and may change by as much as 15% as the wave function, in its present approximation, is improved.