Are all-atom any better than united-atom force fields for the description of liquid properties of alkanes? 2. A systematic study considering different chain lengths

• Published in: Journal of molecular liquids Vol. 354; p. 118829
• Main Authors: da Silva, Guilherme C.Q., Silva, Gabriel M., Tavares, Frederico W., Fleming, Felipe P., Horta, Bruno A.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-05-2022
• Subjects: Benchmark; Force fields; Molecular simulation; n-alkanes; Molecular simulation; Benchmark; n-alkanes; Force fields
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.118829

•An accuracy assessment of many force fields used to describe n-alkanes in molecular dynamics simulations was performed.•The temperature and chain-size dependence of density, heat of vaporization, surface tension and viscosity were analyzed.•Based on a penalty score, the force celds were ranked accordingly to their accuracy.•United-atoms models were comparable or even better than all-atom models in describing the liquid phase of n-alkanes.•Some commonly used force fields were shown to erroneously induce the formation of structured nuclei.
Our previous study assessed the performance of 12 different force fields in describing the liquid phase of n-octane. The present study extends the analysis to n-alkanes of longer chain lengths. The 6 best force fields considered in our previous study were evaluated regarding their accuracy at reproducing the density, heat of vaporization, surface tension, and viscosity of n-dodecane, n-hexadecane, n-eicosane, n-tetracosane, and n-octacosane. The considered force fields were ranked based on the root-mean-squared deviation and normalized root-mean-squared deviation over different properties and compounds. This deviation analysis, combined with the fitting of linear relationships, presented a clear picture of the quality of the chosen models in reproducing the properties of interest. The all-atom version of the CHARMM (CHARMM-AA) and NERD models present a premature solidification behavior. In agreement to the previous study that was limited to n-octane, the united-atoms models led to comparable or even better results than all-atom models in reproducing the properties of liquid phases of alkanes. Overall, the united-atom GROMOS force field performed systematically better than the other force fields in reproducing the liquid-phase properties of the considered alkane molecules.