Tuning partial charges of alkyl alcohols to improve simulated fluid properties

Abstract

Standard simulation interaction parameters sometimes predict liquid properties at variance with experiment, especially for polar liquids. In this work, we systematically scaled the partial charges of three alkyl alcohols to evaluate whether adjusting the partial charges, and thus the electrostatic interactions, can improve agreement with experimental values of key liquid properties, including the dielectric constant, vapor pressure, density, and self-diffusion coefficient. Changing the partial charges also affects liquid structures, which are evaluated through a hydrogen bond analysis. We found that modest adjustment factors applied to all partial charges improve values for computed properties, but too large an adjustment causes string-like aggregation of molecular dipoles and inhibits system dynamics.