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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Charged Soft Matter I

CPP 22.2: Vortrag

Dienstag, 17. März 2015, 09:45–10:00, PC 203

Thermal and structural properties of dense ionic liquids — •Hendrik Bartsch and Markus Bier — Max Planck Institute IS and University of Stuttgart, Germany

The phase behavior and the structure of ionic liquids has been a subject of many theoretical studies, simulations and experiments. However, it has not been investigated so far which features of the underlying Coulomb interaction lead to the properties of ionic liquids. The aim of this work is to answer the fundamental question, whether the long-range character or the valency dependence of the Coulomb interaction determine the thermal and structural properties. In order to investigate the influence of the interaction range a modified Lattice Restricted Primitive Model is considered, where the electrostatic interactions are truncated at finite distance. Structural and thermal properties are obtained via grandcanonical Monte Carlo simulations as functions of the cut-off radius. The critical temperature of the modified LRPM is found to be an order of magnitude too high as compared to the ordinary LRPM of the long-ranged Coulomb interaction. Additionally, we observe a strong dependence of the critical temperature on the cut-off radius which does not appear to converge towards the correct value in the long-range limit. We show by means of an appropriately improved model that this defect does not occur and that the quantitatively correct phase behavior and structure can be obtained if charge neutrality within the interaction range, which corresponds to the perfect screening property, is maintained.