Gas-Liquid critical behaviour

The existence of gas-liquid coexistence in dipolar fluids with no other contribution to attractive interaction than dipole-dipole interaction is a basic question in the theory of fluids. It is perhaps comparable to the freezing transition in the hard sphere fluid discovered in early computer simulation work by Alder and Wainwright in the late fifties. Recently we have shown that a fluid of charged soft dumbbells does exhibit gas-liquid coexistence even for the smallest charge-to-charge separations on the dumbbells. Based on the critical parameters obtained in this limit we intend the direct search for gas-liquid criticality in systems of dipolar soft spheres. If successful this would be the first time that a gas-liquid critical point is found in a purely dipolar system. In addition we plan a detailed comparison between Monte Carlo and Molecular Dynamics results for the length distribution of reversible dipolar chains formed under near critical conditions. This should provide insight into specific unresolved differences between Molecular Dynamics and Monte Carlo Simulations, which may be the reason why no critical point has been seen in dipolar model fluids thus far.

Duration:
01.01.2010 - 31.12.2012

Projectleader:
Prof. Dr. R. Hentschke