NEW METHOD FOR THE EXTRAPOLATION OF FINITE-SIZE DATA TO INFINITE VOLUME

We present a simple and powerful method for extrapolating finite-volum e Monte Carlo data to infinite volume, based on finite-size-scaling th eory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional O(3) and O(infinity) sigma-models. in favorable cases it is possible t o obtain reliable extrapolations (errors of a few percent) even when t he correlation length is 1000 times larger than the lattice.