 
Summary: COMMENTS
Comment on ``An exact quantum Monte Carlo calculation of the
heliumhelium intermolecular potential'' J. Chem. Phys. 115, 4546 ,,2001...
James B. Anderson
Department of Chemistry and Department of Physics, Pennsylvania State University, University Park,
Pennsylvania 16802
Received 15 January 2004; accepted 23 February 2004
DOI: 10.1063/1.1704638
In 1993 we reported ``exact'' quantum Monte Carlo
QMC calculations of potential energies for the interaction
of two helium atoms.1
For the equilibrium internuclear dis
tance of 5.6 bohr, the calculated interaction energy was
11.01 K with an uncertainty of 0.10 K 1 . By 2001
competing methods had achieved similar accuracies in the
interaction energies and we repeated our calculations with
faster computers to obtain higher accuracies.2
With these we
obtained an interaction energy at 5.6 bohr of 10.98 K with
an uncertainty of 0.02 K. Competing methods have again
