Scaling equation of state derived from the pseudospinodal

Starting from the concept of the pseudospinodal, the authors derive an explicit expression for the scaling equation of state applicable to liquid-gas [and universality class (3,1)] systems. The advantages of this equation over other phenomenological equations are: it has no adjustable, unphysical parameters; it is valid in the metastable region; and it can simultaneously predict PVT data and the critical amplitude ratio for specific heat. The equation also fits PVT data as well as other phenomenological equations, is easy to use, and accurately predicts other critical amplitude ratios. It is argued that the success of this equation supports the usefulness of the pseudospinodal, which has been questioned by certain theoretical considerations.