Association effects in the {methanol + inert solvent} system via Monte Carlo simulations. I. Structure.

In this work, the clusters residing in the {methanol + inert solvent} binary system have been characterized using a specific methodology in the framework of Monte Carlo molecular simulations. The cluster classification scheme considered distinguishes into five types: linear chains, cyclic clusters or isolated rings, branched linear chains, branched cyclic clusters, and composite rings. The procedure allows one to compute the next rich structural information: the fraction of molecules in the monomer or associated state, the fraction of each type of aggregate with a given size (and of molecules belonging to them), and the most probable and average cluster size for each type; likewise, the degree of branching in branched linear chains and the size distribution of the inner ring in branched cyclic clusters can be quantified. Specifically, all these properties were obtained for the {Optimized Potential for Liquid Simulation methanol + Lennard-Jones spheres} system at 298.15 K and 1 bar throughout the composition range. The results have provided a complete structural picture of this mixture describing comprehensively the effect of dilution into the hydrogen-bonded network of the pure associated fluid.