Molecular dynamics simulations are commonly used in chemistry to study the thermodynamic, structural, and dynamic properties of model liquid systems. A force field is a mathematical expression for the potential energy of the model system as a function of the positions of the particles of the system (atoms or pseudo-atoms), including the parameters therein. Force fields differ from each other because they are developed for different model systems, are parameterized differently, and describe the real system in a different level of detail. In this work, we performed molecular dynamics simulations of a model of hexan-1-ol using different force fields (AMBER, CHARMM, OPLS, TraPPE, and GROMOS) with the simulation software package GROMACS. Various radial and spatial distribution functions, density, diffusion coefficient, end-to-end distance and enthalpy of vaporization were calculated from the simulation results. The radial distribution functions show that the different hexan-1-ol models have different structural properties of the liquid phase. The united-atom models (TraPPE and GROMOS) show a greater tendency to form hydrogen bonds than the all-atom models (OPLS, AMBER, and CHARMM). The calculated density of all model systems agrees well with the experimental value, except for the model AMBER. The best agreement of the calculated diffusion coefficient with the experimental value was obtained with the OPLS and GROMOS models. The calculated enthalpy of vaporization of the TraPPE and OPLS models agrees well with the experimental value, while the other models do not give such agreement. From the intramolecular spatial distributions and the distribution of the end to-end molecular distance, we can conclude that the model molecules are most flexible in the GROMOS model and most rigid in the TRAPPE model.
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