Supporting Information: Toward learned chemical perception of force field typing rules

The Open Force Field Initiative seeks to to automate force field development in order to advance force fields and improve accuracy (openforcefield.org). An important part of this effort includes automating the determination of chemical perception --- that is, the way force field parameters are assigned to a molecule based on chemical environment. We developed a novel technology for this purpose, termed SMARTY. It generalizes atom typing by using direct chemical perception with SMARTS strings adopting a hierarchical approach to type assignment. The SMARTY technology enables creation of a move set in atom-typing space that can be used in a Monte Carlo optimization. We demonstrate the power of this approach with a fully automated procedure that is able to re-discover human-defined atom types in the traditional small molecule force field parm99/parm@Frosst. We furthermore extend this tool to direct chemical perception of valence types (bonds, angles, and torsions) via SMIRKS strings to crea...