Extension of the TraPPE-UA force field to the simulation of vapor–liquid phase equilibria of vinyl acetate system

Multiscale Simulation of Vinyl Acetate Systems Applied in the Industrial Gas Separation Column

“…Kamath has extended the TraPPE-UA force field for methyl acetate and studied liquid-phase properties of the molecules at room temperature. Furthermore, an extension of NERD united-atom force field for esters was used to predict liquid-phase properties for triglyceride by Khare et al In our earlier work, an extended TraPPE-UA force field for VAc has been proposed based on the Lennard-Jones plus point charge functional model, and the simulation results of thermodynamic properties of VAc were in good agreement with the experimental data, suggesting that the extended TraPPE-UA force field is suitable for the VAc system.…”

“…In this work, the molecular model of VAc was built based on the extensional TraPPE-UA force field, where parameters for the CH3*­(sp3), Cco = o­(sp2), O = c­(sp2), Occ­(sp3), and CH2 = *­(sp2) groups were taken directly from the TraPPE-UA force field. , All geometric data for valence terms of the CHo = c­(sp2) group, such as bond lengths, angles, bending, and torsional potentials, were directly taken from previous installments of the TraPPE-UA and OPLS-UA force fields. However, the L-J parameters of the CHo = c (sp2) group were missing in the primitive TraPPE-UA force field, which were obtained by fitting the quantum chemistry calculation results of its intermolecular interactions with the probe molecule in our previous research, and the point charges were also determined by ESP analysis of ab initio calculations performed at the MP2/6-311G (d, p) level. More details on parameterization of the VAc molecular model were given in our earlier work …”

“…However, the L-J parameters of the CHo = c (sp2) group were missing in the primitive TraPPE-UA force field, which were obtained by fitting the quantum chemistry calculation results of its intermolecular interactions with the probe molecule in our previous research, and the point charges were also determined by ESP analysis of ab initio calculations performed at the MP2/6-311G (d, p) level. More details on parameterization of the VAc molecular model were given in our earlier work …”

“…The intramolecular and intermolecular parameters between CH*­(sp) groups were obtained from the optimized structure of the C 2 H 2 molecule calculated by the quantum chemistry method at the MP2/6-311G (d, p) level. Among them, the L-J parameters of the CH*­(sp) group were determined by fitting the interaction energies between the Ne atom and C 2 H 2 molecule in a three-dimensional space, which were scanned along the direction between their optimized structures, and the fitting curve is shown in Figure S1. Moreover, point charges of CH*­(sp) groups were also determined by ESP analysis at the MP2/6-311G (d, p) level.…”

“…Aiming at these systems which are missing from experimental data and difficult to measure, the Gibbs Ensemble Monte Carlo (GEMC) method has been developed as a powerful tool, which can not only predict the VLE behavior, but also give insights into the microstructure of the systems. , The accuracy of the calculated VLE data relies on the force field parameters of the compounds . Among many molecular force fields, TraPPE-UA shows good performance in VLE prediction because of its high sensitivity to thermodynamics.…”