Parametric Representation of the Equation of State Near A Critical Point

Abstract

A parametric representation of the usual thermodynamic variables in the neighborhood of a critical point is proposed in terms of new variables $r$ and $\ensuremath{\theta}$. The representation is chosen so that the "scaling-law" behavior is entirely contained in the $r$ dependence, the $\ensuremath{\theta}$ dependence being free of critical singularities. Preliminary calculations show that the $\ensuremath{\theta}$ dependence may be chosen to have a rather simple form both in a ferromagnet and in fluids.