Molecular Dynamics Simulation for the Calibration of the OPLS Force Field Using DFT Derived Partial Charges for the Screening of Alkyl Phosphate Ligands by Studying Structure, Dynamics, and Thermodynamics

Molecular dynamics (MD) simulations were performed to calibrate the all-atom optimized potential for liquid simulations (OPLS-AA) force field using partial quantum charges calculated from four different population analysis methods: Mulliken, Lowdin, NPA, and ChelpG for predicting the thermophysical properties of pure liquids like tri-n-butylphosphate (TBP), tri-isoamylphosphate (TiAP), triethylphosphate (TEP), and dodecane to determine a potential solvent for the nuclear fuel cycle. The structural, dynamic, and thermodynamic properties were calculated in NVT ensembles by introducing the partial charges on each atom calculated from density functional theory (DFT). The calculated structural and dynamic properties were affected by the different partial charges on TBP, TiAP, and TEP. The estimated liquid density employing partial charges obtained from Mulliken population analysis with OPLS force field leads to an excellent agreement with the experimental data (within 0.36–1.41%). The diffusivity and the pair ...