Rapid parameterization of small molecules using the force field toolkit

TLDR

The inability to rapidly generate accurate and robust parameters for novel chemical matter limits the application of molecular dynamics simulations, especially in drug discovery, despite generalized force fields such as GAFF and CGenFF still facing technical challenges. The study introduces ffTK to streamline ligand parameterization by automating tasks and providing a graphical user interface. ffTK, distributed as a VMD plugin, offers a clear workflow that generates quantum‑mechanical target data, runs multidimensional optimizations, and analyzes parameter performance to produce CHARMM‑compatible parameters. ffTK‑generated parameters matched CGenFF in reproducing pure‑solvent properties within 15 % error and solvation free energies within ±0.5 kcal/mol.

Abstract

The inability to rapidly generate accurate and robust parameters for novel chemical matter continues to severely limit the application of molecular dynamics simulations to many biological systems of interest, especially in fields such as drug discovery. Although the release of generalized versions of common classical force fields, for example, General Amber Force Field and CHARMM General Force Field, have posited guidelines for parameterization of small molecules, many technical challenges remain that have hampered their wide-scale extension. The Force Field Toolkit (ffTK), described herein, minimizes common barriers to ligand parameterization through algorithm and method development, automation of tedious and error-prone tasks, and graphical user interface design. Distributed as a VMD plugin, ffTK facilitates the traversal of a clear and organized workflow resulting in a complete set of CHARMM-compatible parameters. A variety of tools are provided to generate quantum mechanical target data, setup multidimensional optimization routines, and analyze parameter performance. Parameters developed for a small test set of molecules using ffTK were comparable to existing CGenFF parameters in their ability to reproduce experimentally measured values for pure-solvent properties (<15% error from experiment) and free energy of solvation (±0.5 kcal/mol from experiment).