FINITE-SIZE-SCALING OF THE GROUND-STATE PARAMETERS OF THE 2-DIMENSIONAL HEISENBERG-MODEL

The ground-state parameters of the two-dimensional S=1/2 antiferromagn etic Heisenberg model are calculated using the stochastic series expan sion quantum Monte Carlo method for LXL lattices with L up to 16. The finite-size results for the energy E, the sublattice magnetization M, the long-wavelength susceptibility chi(perpendicular to)(q=2 pi/L), an d the spin stiffness rho(s), are extrapolated to the thermodynamic lim it using fits to polynomials in 1/L, constrained by scaling forms prev iously obtained from renormalization-group calculations for the nonlin ear sigma model and chiral perturbation theory. The results are fully consistent with the predicted leading finite-size corrections, and are of sufficient accuracy for extracting also subleading terms. The subl eading energy correction (similar to 1/L-4) agrees with the chiral per turbation theory to within a statistical error of a few percent, thus providing numerical confirmation of the finite-size scaling forms to t his order. The extrapolated ground-state energy per spin is E=-0.66943 7(5). The result from previous Green's function Monte Carlo (GFMC) cal culations is slightly higher than this valve, most likely due to a sma ll systematic error originating from ''population control'' bias in GF MC. The other extrapolated parameters are M=0.3070(3), rho(s)=0.175(2) , chi(perpendicular to)=0.0625(9), and the spin-wave velocity c=1.673( 7). The statistical errors are comparable with those of previous estim ates obtained by fitting loop algorithm quantum Monte Carlo data to fi nite-temperature scaling forms. Both M and rho(s) obtained from the fi nite-T data are, however, a few error bars higher than the present est imates. It is argued that the T=0 extrapolations performed here are le ss sensitive to effects of neglected higher-order corrections, and the refore should be more reliable. [S0163-1829(97)01841-9].