Physical review. B, Condensed matter
Anisotropic bond percolation in two dimensions
Daniel P. Arovas, R. N. Bhatt, Boris Shapiro
Abstract
A new single-parameter renormalization-group equation is formulated for anisotropic bond percolation in two dimensions using a position-space renormalization approach. The new equation yields the exact critical line ${p}_{x}+{p}_{y}=1$ within both the Migdal-Kadanoff decimation and cell renormalization schemes. For large anisotropy, however, an additional critical line appears leading to a spurious divergence in the correlation-length critical exponent. An alternative scheme, which does not preserve the exact critical surface, but yields a correlation-length exponent relatively independent of anisotropy, is also examined.