GROMACS gains Amber ff14SB and ff19SB force field ports

Vedran Miletić and collaborators have ported the Amber ff14SB and ff19SB protein force fields to GROMACS, with the work now merged into the project rather than distributed separately. The ff19SB port required extending GROMACS itself to support amino-acid-specific corrections to backbone conformational energy. The team validated the ports against Amber by comparing interaction energies and ubiquitin simulation behavior. Miletić has also contributed to GROMACS maintenance, including Windows build support via MinGW and Wine, which exposed cross-platform bugs in shared code.

What the Amber ports required

• ff19SB backbone corrections: GROMACS was extended to support amino-acid-specific corrections to protein backbone conformational energy, not a simple parameter file translation
• Cross-engine precision work: Differences in fundamental constants, parameter precision, and improper dihedral atom ordering between Amber and GROMACS had to be reconciled
• Validation method: Compared individual interaction energies and ubiquitin conformational behavior in long simulations against Amber reference
• Windows build testing: MinGW/Wine builds exposed zero-coordinate trajectory-reading bugs and time-selection state leaks between analysis-tool invocations
• Integration: Force fields are now shipped with GROMACS itself, removing the need for users to locate and evaluate external downloads

Why it matters

Integrating these widely used Amber force fields directly into GROMACS removes a friction point for researchers moving between simulation packages and reduces the risk of parameter translation errors. The Windows build work, while serving a smaller user base, improved code quality for all platforms by exposing latent bugs.