# gmx_ffconv: A Fast, User-Friendly Semi-Automated All-Atom Force Field Converter for GROMACS

## TL;DR

gmx_ffconv is a tool that simplifies converting molecular systems between different force fields in GROMACS, saving time and reducing errors.

## Contribution

The novelty lies in automating atom ordering and naming mismatches using molecular graph matching for force field conversion.

## Key findings

- gmx_ffconv successfully validated on systems ranging from small ligands to large solvated systems with over two million atoms.
- The tool enables identical starting coordinates across force fields, improving simulation comparability.
- It eliminates the need for manual reordering or scripting during force field conversion.

## Abstract

This application note presents gmx_ffconv, a command-line
tool
developed to facilitate the conversion of systems between all-atom
force fields within GROMACS. As different force fields use their own
naming conventions and atom ordering, force field conversion within
GROMACS is usually a time-consuming, error-prone process. gmx_ffconv
resolves atom ordering and naming mismatches between different force
fields by reordering the coordinate file via molecular graph matching.
This enables the use of identical starting coordinates across force
fields, facilitating comparative simulations without requiring manual
reordering or scripting. The tool has been validated on a broad range
of systems, from small, nonstandard ligands to large, solvated heterogeneous
systems with more than two million atoms. gmx_ffconv is available
on GitHub: github.com/Jassu1998/gmx_ffconv.