D. Blume et Ch. Greene, Quantum corrections to the ground-state energy of a trapped Bose-Einstein condensate: A diffusion Monte Carlo calculation - art. no. 063601, PHYS REV A, 6306(6), 2001, pp. 3601
The diffusion Monte Carlo method is applied to describe a trapped atomic Bo
se-Einstein condensate at zero temperature, fully quantum mechanically and
nonperturbatively. For low densities, n(0)a(3)less than or equal to 2x10(-3
) [n(0) peak density; a, s-wave scattering length], our calculations confir
m that the exact ground-state energy for a sum of two-body interactions dep
ends to a good approximation on only the atomic-physics parameter a, and no
other details of the two-body model potential. Corrections to the mean-fie
ld Gross-Pitaevskii energy range from being essentially negligible to about
20% for N=2-50 particles in the trap with positive s-wave scattering lengt
h a = 100-10 000 a.u. Our numerical calculations confirm that inclusion of
an additional effective potential term in the mean-field equation, which ac
counts for quantum fluctuations [see, e.g., E. Braaten and A. Nieto. Phys.
Rev. B 56, 14 745 (1997)], leads to a greatly improved description of trapp
ed Bose gases.