Towards an analytical theory for charged hard spheres

Abstract

Ion mixtures require an exclusion core to avoid collapse. The Debye Hueckel (DH) theory, where ions are point charges, is accurate only in the limit of infinite dilution. The mean spherical approximation (MSA) is the embedding of hard cores into DH, and is valid for higher densities. The properties of any ionic mixture can be represented by the single screening parameter Γ which for the equal ionic size restricted model is obtained from the Debye parameter κ. This Γ representation, the binding mean spherical approximation (BIMSA), is also valid for complex / associating systems, such as the general n-polyelectrolytes. The BIMSA is the only theory that satisfies the infinite dilution limit of the DH theory for any chain length. Furthermore, the contact pair distribution function calculated from our theory agrees with the Monte Carlo of Bresme ea.(Phys. Rev. E, 1995, 51, 289).

Crystallization limits of the two-term Yukawa potentials based on the entropy criterion

“…15,16 The MSA calculations were examined vis à vis the Monte Carlo ͑MC͒ data in Broccio et al 15 It was found that the MSA according to Blum and Hoye 4 performed reasonably well at weak attraction ͑K 1 Ͻ 2.5͒, but deteriorated for strong attraction ͑K 1 Ͼ 2.5͒, while the hypernettedchain ͑HNC͒ equation 18 gave more accurate structure factors S͑q͒ over the whole range of K 1 studied. It is conceivable that the more modern versions of MSA as given by Blum and Arias 19,20 for the n-Yukawa potentials will also give good results. Broccio et al 15 in 2006 presented a very thorough IE study.…”