Molecular Dynamics of Binary Fluids in the Region of the Critical Mixing Point: II. The Static and Dynamic Behaviour

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Abstract
In this second part of our report we continue the description of our molecular dynamics (MD) investigations on partially miscible binary fluids near the critical mixing point.1 Whereas our first article has reported the basic aspects of our attempt to simulate near-critical states, the present paper describes and discusses the entirely calculated results of our simulations. The three binary fluids, CH4/CF4; Ne/Kr; He/Xe have been considered for an MD-simulation including the wider vicinity of the critical mixing point. The thermodynamic and transport properties of these mixtures were satisfactorily reproduced at the region outside the critical point. Near-critical conditions for the model systems were indicated by an increased correlation length and a slowing down of the relaxation processes. The behaviour of these quantities is in essential accordance with the experimental data for similar near-critical systems. Changes of the pair-distribution functions showed alterations of the microscopic structure of the systems in the region of the critical point. The self-diffusion coefficients, however, exhibited no anomalies at near-critical conditions according to nmr-measurements on binary liquid systems. Apparently, we have for the first time succeeded in describing theoretically a nearcritical state of binary fluids.