%0 Journal Article %T Modified Extrapolation Length Renormalization Group Equation %A Jacob Morris %A Joseph Rudnick %J Physics %D 1999 %I arXiv %X A modified renormalization group equation for the inverse extrapolation length $c$ is derived by considering the phase shifts of order parameter fluctuations. The resulting non-linear equation is also derived using standard methods and some additional assumptions. The associated renormalized flow $c(l)$ exhibits the correct behavior near both the special and ordinary fixed points and in particular yields a canonical scaling of $c$ with cross-over exponent $\phi_{\rm ord} = -\nu$ near the ordinary transition. %U http://arxiv.org/abs/cond-mat/9908071v1