engleski

Local fluctuations in ethanol mixtures

We study different ethanol mixtures using classical molecular dynamics computer simulations. The theory of fluctuations, developed by Kirkwood and Buff in the 50's [1], allows us to connect integrals of radial distribution functions, obtained through simulations, with a variety of thermodynamic quantites, such as partial molar volumes, compressibility and most importantly, the thermodynamic factor. The value of thermodynamic factor is twofold. Firstly, it is an indicator of the stability of a mixture, with respect to mixing or demixing, since it can be written as a second derivative of the Gibbs free energy with respect to concentration. Secondly, it is particularly useful in comparing experimental and simulation results for diffusion coefficients. Here, we look for the most precise and accurate ways of calculating the thermodynamic factor from finite size systems and see what we can learn about hydrogen bonding associative mixtures and their deviation from ideality. Understanding the structural characteristics on molecular level is important for the understanding of more complex biological structures and processes. [1] JG Kirkwood, F Buff (1951) J. Chem. Phys. 19, 774

binary-mixtures ; ethanol ; Kirkwood-Buff-integrals

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