Molecular modeling aids diverse fields in chemistry, including high-profile applications to predict the dynamics of large molecular systems in solution. These simulations also allow for predictive measures of different physical properties such as a molecule’s solubility or preferred conformation. The underlying technology in these simulations is the force field. Force fields provide potential energy functions that dictate the interactions between atoms described by Newton's equations of motion. An issue in current force fields are the energetics and geometries around a trivalent bonded nitrogen center. Current force fields predict geometries of nitrogen centers to be planar, however in reality these geometries range from planar to pyramidal based on their chemical environments. We introduce a framework and approach to fitting improper and angle parameters for trivalent nitrogens that yield better energetics and geometries for selected molecules with a relatively minimal expansion of parameter space. This presentation lays the groundwork for an approach to fit improper and angle parameters for larger sets of trivalent nitrogens and other trivalent bonded atom centers such as carbon or phosphorus.

Fitting improper torsion parameters for atomistic force fields

2019 Fall National Meeting

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