Universal amplitudes in the finite-size scaling of three-dimensional spin models

In a Monte Carlo study using a cluster update algorithm we investigate finite-size scaling (FSS) of the correlation lengths of several representatives of the class of three-dimensional classical O(n) symmetric spin models on the geometry T-2 X R. For all the models we find strong evidence of a linear relation between FSS amplitudes and scaling dimensions when applying antiperiodic instead of periodic boundary conditions across the torus. This type of scaling relation can be proven analytically for systems on two-dimensional strips with periodic boundary conditions using conformal field theory.