Systematic parameterization procedure to develop force fields for molecular fluids using explicit water.

Abstract The three steps systematic parameterization procedure, 3SSPP, to develop force fields of polar liquids proposed by our group (J. Chem. Theory Comput. 2015 , 11, 68 3) is reviewed. The method allows obtaining independently the charge distribution and Lennard-Jones parameters of pure components if the experimental dielectric constant, surface tension and liquid density are used as target properties. Different methods to determine the partial atomic charges from electronic structure calculations of isolated polar molecules are analyzed. It is shown that the charge distribution plays an important role in several properties of pure components and binary mixtures, including solubility. Molecular dynamics simulations of 12 typical polar liquids in aqueous solutions show that the TraPPE-UA force field, in general, underestimates the experimental solubility in a liquid-liquid equilibrium at room conditions. The 3SSPP is used to reparameterize the TraPPE-UA non-bonding parameters of liquid 1-propanol, 2-pentanone and methyl acetate using scaled atomic charges from the Hirshfeld partition scheme. The new parameters predict the correct solubility of 1-propanol in water but fail to reproduce that of the other two molecules. The new parameterization procedure, 4SSPP, is extended to include the solubility as a target property. The solubility is reproduced by modifying the charge distribution obtained for the pure components keeping constant the molecular dipole moment and Lennard-Jones parameters. The method is applied to 2-pentanone and methyl acetate as pure components and their mixtures with water. The target properties of the pure components are almost unaffected after the refining process of the charge distribution. The liquid-vapor phase diagram is also determined for a single component. The results show that the use of an explicit solvent, water in this case, in a simulation is a good way to improve, with a small additional computational cost, the force field parameters of pure components to be used in computer simulations in multicomponent systems. The new parameters are used to obtain the liquid density of 1-propanol/methanol and methyl acetate/methanol mixtures and excellent agreement with experimental data is found. [ABSTRACT FROM AUTHOR]