Published October 21, 2025 | Version 2025.10.1
Software Open

openforcefield/openff-forcefields

  • 1. Open Force Field Consortium, Open Molecular Software Foundation, Davis, CA, USA
  • 2. Open Free Energy, Open Molecular Software Foundation, Davis, CA, USA
  • 3. Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA
  • 4. Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
  • 5. Department of Chemistry, University of California Irvine, Irvine, CA, USA
  • 6. School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1, 7RU, United Kingdom
  • 7. Department of Chemistry, University of California Davis, Davis, CA, USA
  • 8. OpenEye Scientific Software, Santa Fe, NM, USA

Description

This release adds openff_no_water-3.0.0-alpha0.offxml and openff_no_water_unconstrained-3.0.0-alpha0.offxml. This force field is applicable to druglike molecules consisting of the elements C, H, O, N, P, S, F, Cl, Br, and I, and the monoatomic ions Li+, Na+, K+, Rb+, F-, Cl-, Br-, and I-.

We're making an early alpha version of a SMIRNOFF protein force field available. While this FF has passed our initial rounds of benchmarks, there are more rounds to evaluate, and our previous experience leads us to expect that this will not be the FF that we release as Rosemary (openff-3.0.0). However we wanted to give users and developers an early look to begin their planning. We anticipate that the full openff-3.0.0 release will have the same structure as this alpha protein FF, in terms of using AshGC/NAGL charges (not library charges) and the approximate number and composition of SMIRKS parameters.

This force field is a research tool and does not contain a water model, and probably has other pointy edges. It's likely you'll get the best results using OPC3 as the water model. If you do not include a water model, the FF will still work, but your waters will be assigned hydroxyl parameters, will lack angle constraints, and will be very unphysical.

Limited training data and code is available for this alpha force field at https://zenodo.org/records/17401377 . This is the DOI we'd prefer researchers use to cite this FF.

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