Effective field theory predicts that the leading nonuniversal effects in th
e homogeneous Bose gas arise from the effective range for S-wave scattering
and from an effective three-body contact interaction. We calculate the lea
ding nonuniversal contributions to the energy density and condensate fracti
on and compare the predictions with results from diffusion Monte Carlo calc
ulations by Giorgini, Boronat, and Casulleras [Phys. Rev. A 60, 5129 (1999)
]. We give a crude determination of the strength of the three-body contact
interaction for various model potentials. Accurate determinations could be
obtained from diffusion Monte Carlo calculations of the energy density with
higher statistics.