We investigate the validity of the method of computing ground-state energies, at a given angular momentum, with Monte Carlo methods applied to the functional integral formulation containing pairing fields. Calculations have been performed for several erbium isotopes and a few dysprosium isotopes. It is found that some residual sign fluctuations, which seem to be associated with a small neutron number above the $N=82\mathrm{}$ shell closure, are present, but that they do not affect the feasibility of the calculations. Such sign fluctuations disappear as the neutron number is increased. Also, an efficient improved method for the computation of the functional integral in the case of an odd number of particles is presented. The Monte Carlo method of Metropolis et al. [J. Chem. Phys. 21, 1087 (1953)] is used in the evaluation of expectation values.

• Received 27 March 2001

DOI:https://doi.org/10.1103/PhysRevC.64.034318