Crossover behavior for long reptating polymers - art. no. 010801

The Rubinstein-Duke model for polymer reptation is analyzed by means of den sity matrix renormalization techniques. It is found that the crossover in t he scaling behavior of polymer renewal time (or viscosity) arises from the competing effect of the contribution due to tube length fluctuations and hi gher-order corrections, which are of opposite sign. Experiments which ought to emphasize both contributions are suggested. The exponent describing the subleading scaling behavior of the diffusion coefficient is also investiga ted.