Crossover parametric equation of state for Ising-like systems

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 64; no. 2 Pt 2; p. 026125
• Main Authors: Agayan, V A, Anisimov, M A, Sengers, J V
• Format: Journal Article
• Language: English
• Published: United States 01.08.2001
• ISSN: 1539-3755; 1550-2376
• DOI: 10.1103/PhysRevE.64.026125

We present a parametric equation for the thermodynamic properties in the critical region of three-dimensional Ising-like systems which include fluids and fluid mixtures. The equation of state incorporates a crossover from singular Ising behavior asymptotically close to the critical point to classical (mean-field) behavior further away from the critical point, characterized by two physical crossover parameters: a coupling constant related to the strength and range of molecular interactions and a "cutoff" wave number for the critical fluctuations. In the asymptotic Ising limit, the crossover equation reproduces the most recent theoretical estimates for the universal ratios of the leading and correction-to-scaling critical amplitudes. The equation has been tested by comparing it with recent experimental thermodynamic-property data for 3He near its vapor-liquid critical point.