Abstract
Monte Carlo calculations on off-lattice chains with various ratios lambda of bead diameter to bond length show that gamma and gamma ' in mean square h=aNgamma or mean square r=a'Ngamma ', respectively, are not 6/5 throughout but depend on lambda . It is generally accepted that the theoretical predictions of the two-parameter theory do not depend on the kind of interaction potential between non-bonded beads. This assumption, however, proves to be wrong. The hard-sphere potential employed in this work yields results inconsistent with those of the perturbation theory using a pseudopotential with a delta function.