Condensed Matter Physics, 2016, vol. 19, No. 2, 23603
DOI:10.5488/CMP.19.23603
arXiv:1603.07132
Title:
Two and threephase equilibria in polydisperse Yukawa hardsphere mixture. High temperature and mean spherical approximations
Author(s):

T.V. Hvozd
(Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine)
,


Y.V. Kalyuzhnyi
(Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine)

Phase behavior of the Yukawa hardsphere polydisperse mixture with high degree of polydispersity is studied using high temperature approximation (HTA) and mean spherical approximation (MSA).
We have extended and applied the scheme developed to calculate the phase diagrams of polydisperse mixtures described by the truncatable free energy models, i.e., the models with Helmholtz free
energy defined by the finite number of the moments of the species distribution function. At high degree of polydispersity, several new features in the topology of the twophase diagram have been observed:
the cloud and shadow curves intersect twice and each of them forms a closed loop of the ellipsoidallike shape with the liquid and gas branches of the cloud curve almost coinciding.
Approaching a certain limiting value of the polydispersity index, the cloud and shadow curves shrink and disappear. Beyond this limiting value, polydispersity induces the appearance of
the threephase equilibrium at lower temperatures. We present and analyze corresponding phase diagrams together with distribution functions of three coexisting phases. In general,
good agreement was observed between predictions of the two different theoretical methods, i.e., HTA and MSA. Our results confirm qualitative predictions for the threephase
coexistence obtained earlier within the framework of the van der Waals approach.
Key words:
polydispersity, phase coexistence, colloidal systems, Yukawa potential
PACS:
64.75.g, 82.70.Dd
