  A new Monte Carlo method for computing thermodynamical properties of very
large polyelectrolytes is presented. It is based on a renormalization group
relating the original polymer to a smaller system, where in addition to the
naively rescaled forces, a corrective nearest-neighbor interaction originating
from the short distance Coulomb cutoff is introduced. The method is derived for
low T but is in the unscreened case valid for all T. Large polymers with N
monomers are emulated by Monte Carlo calculations on smaller systems, K=N/Q.
The computational gain of the method is Q^3. It is explored with emphasis on
room temperature. Results for N=10000 are presented.
