Equation of state and liquid-vapor equilibrium of polarizable Stockmayer fluids |
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Authors: | Rocha-Ichante Adrián del Río Fernando Ávalos Edgar |
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Institution: | Departamento de Fi?sica, Universidad Auto?noma Metropolitana, Iztapalapa, Apdo 55 534, Me?xico DF 09340, Me?xico. arirocich@yahoo.com.mx |
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Abstract: | In this work we develop the concept of an effective potential to obtain the equation of state of polarizable Stockmayer (PSM) fluids. This potential consists of a Lennard-Jones function with appropriate energy and distance parameters that depend on the reduced dipolar moment μ(?) and polarizability α(?). The approach deals accurately with polarizable SM fluids with μ(?)≤2.0 and α(?)≤0.1. However, prediction of second virial coefficients is reliable up to μ(?)≤4.0. When the low-density sphericalized potential is used at moderate and large densities, the effect of the dipole-dipole attraction is overestimated in agreement with an effect previously found in the literature. This effect can be traced back to a frustration mechanism due to the interaction between three and more dipoles. We propose a model to account for this frustration effect and are able to reproduce the vapor-liquid equilibrium of polarizable SM fluids in agreement with simulated results from the literature. Molecular dynamics simulations were carried out to show that the effective SM fluid has a radial distribution function very close to that of the true SM system. |
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