The mathematical structure imposed by the thermodynamic critical point motivates an approximant that synthesizes two theoretically sound equations of state: the parametric and the virial. The former is constructed to describe the critical region, incorporating all scaling laws; the latter is an expansion about zero density, developed from molecular considerations. The approximant is shown to yield an equation of state capable of accurately describing properties over a large portion of the thermodynamic parameter space, far greater than that covered by each treatment alone.
(PDF) Communication: Analytic continuation of.... Available from: https://www.researchgate.net/publication/281118214_Communication_Analytic_continuation_of_the_virial_series_through_the_critical_point_using_parametric_approximants?enrichId=rgreq-6fbb976f00c00351103c210434668aad-XXX&enrichSource=Y292ZXJQYWdlOzI4MTExODIxNDtBUzoyNjQ4ODk5MTg4MTYyNTZAMTQ0MDE2NjA4NjEzNg%3D%3D&el=1_x_2&_esc=publicationCoverPdf [accessed Jul 23 2018].