title: Coexistence and criticality in size-asymmetric hard-core electrolytes
abstract: Liquid-vapor coexistence curves and critical parameters for hard-core 1:1 electrolyte models with diameter ratios lambda = sigma(-)/sigma(+) = 1 to 5.7 have been studied by fine-discretization Monte Carlo methods. Normalizing via the length scale sigma(+/-) = 1 / 2(sigma(+)+sigma(-)), relevant for the low densities in question, both T(*)(c) ( = k(B)T(c)sigma(+/-)/q(2)) and rho(*)(c) ( = rho(c)sigma(3)(+/-)) decrease rapidly (from approximately 0.05 to 0.03 and 0.08 to 0.04, respectively) as lambda increases. These trends, which unequivocally contradict current theories, are closely mirrored by results for tightly tethered dipolar dimers (with T(*)(c) lower by approximately 0%-11% and rho(*)(c) greater by 37%-12%).
authors.affiliation: Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2431, USA.
authors.initials: JM
authors.lastname: Romero-Enrique
authors.initials: G
authors.lastname: Orkoulas
authors.initials: AZ
authors.lastname: Panagiotopoulos
authors.initials: ME
authors.lastname: Fisher