Eur. Phys. J. E (2005) 16: 167-178
https://doi.org/10.1140/epje/e2005-00018-9

Regular Articles

Molecular multivalent electrolytes: microstructure and screening lengths

¹ Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, A.P. 14-740, 07000, México D.F., Mexico
² Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, 60208, USA
³ Supercomputing Research Department, Supercomputing Center, Korea Institute of Science and Technology Information, Yusong-Gu, Eoeun-Dong 52, Daejon, 305-806, Korea

^* e-mail: m-olvera@northwestern.edu

Received: 30 July 2004
Published online: 22 February 2005

Abstract

We study small rod-like molecular electrolytes solutions with their corresponding atomic counterions. The asymptotic length scales (decay length and wavelength) of the structural correlations are analyzed using the formalism of the dressed interaction site theory (DIST). The correlation functions are determined using the reference interaction site model equation complemented with a mixed approach in which the hypernetted-chain closure is used for the repulsive interactions, and the mean spherical approximation is used for the attractive interactions. The results from this scheme are in good agreement with the Monte Carlo computer simulations reported here. The asymptotic properties of the correlation functions of this molecular system are compared against those corresponding to two related simple (atomic) electrolyte models. The main conclusion is that the molecular structure of the ions lowers by two orders of magnitude the concentration at which the transition from monotonic to oscillatory decay occurs.