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Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic fluorinated organic compounds that are indispensable in various applications, from consumer products to scientific research, due to their unique chemical and physical properties. Recently, these compounds have been found to be hazardous to both the environment and human health, and their remediation poses numerous challenges due to their stability and chemical inertness. Therefore, structural analysis of PFAS compounds is crucial to address this issue. Molecular dynamics (MD) simulations are an important tool in this regard as they allow the study of atomic behavior over time. In this work, we have focused on fluorinated alcohols. MD simulations were performed with the liquid 2,2,2-trifluoroethanol system (TFE) to determine how different force fields behave in describing the properties of fluorinated compounds. We have investigated six different force fields: TRAPPE, GROMOS-UA, GROMOS-AA, CHARMM, AMBER and OPLS. The suitability of these force fields for the prediction of structural and dynamic properties was evaluated by comparing the calculated results of simulation model systems with experimental X-ray scattering data, conformational analyses from the literature and certain thermodynamic quantities such as density and molecular diffusion coefficient. It was found that the TRAPPE, GROMOS-UA and GROMOS-AA force fields better describe the intermolecular correlations, while CHARMM, AMBER and OPLS are better suited to describe the intramolecular characteristics of TFE. The latter more accurately predicted the conformational forms of the molecules (gauche vs. trans), which we observed from the intramolecular spatial distribution functions and the average molecular end-to-end distances. On the other hand, the position of the maximum of the theoretical scattering curves was in better agreement with the experimental peak with the TRAPPE, GROMOS-UA and GROMOS-AA force fields.
Theoretical Biophysics and Soft Matter Group