What's Changed Improvements Convert all amber ions (see https://github.com/openmm/openmm/issues/3663 for more detail) one-to-one using Amber ion frcmod files (from AmberTools 22) into OpenMM xml files with the same names and the same contents. by @mattwthompson & @aizvorski in https://github.com/openmm/openmmforcefields/pull/242 & https://github.com/openmm/openmmforcefields/pull/239 SystemGenerator should only add barostat if system is periodic. Solves https://github.com/openmm/openmmforcefields/issues/252 by @jchodera in https://github.com/openmm/openmmforcefields/pull/253 Fix OPC3 bond length. In the Amber implementation of the OPC3 water model at ffxml/amber/opc3.xml, the H-O bond length was too large by a factor of 10. by @mattwthompson in https://github.com/openmm/openmmforcefields/pull/273 raise ForceException if a custom force is found. by @mattwthompson in https://github.com/openmm/openmmforcefields/pull/292 Allow an offxml string to be used as a small molecule force field for the SystemGenerator and SMIRNOFFTemplateGenerator for example: ```python "Try and load a OFFXML string into a system generator object" from openmmforcefields.generators import SystemGenerator from openff.toolkit.typing.engines.smirnoff import ForceField from openff.toolkit.topology import Molecule import openmm load the ff ff = ForceField("openff-2.0.0.offxml") create a system generator system_gen = SystemGenerator( forcefields=['amber/ff14SB.xml', 'amber/tip3p_standard.xml'], small_molecule_forcefield=ff.to_string() ) mol = Molecule.from_smiles("CC") system = system_gen.create_system(topology=mol.to_topology().to_openmm(), molecules=mol) with open("system.xml", "w") as output: output.write(openmm.XmlSerializer.serialize(system)) ``` by @jthorton in https://github.com/openmm/openmmforcefields/pull/288 Support system and template generator for Espaloma 0.3. (espaloma 0.2. is no longer supported) by @ijpulidos in https://github.com/openmm/openmmforcefields/pull/293 CI Bump codecov/codecov-action from 3.1.0 to 3.1.1 by @dependabot in https://github.com/openmm/openmmforcefields/pull/238 Switch to setup-micromamba by @mattwthompson in https://github.com/openmm/openmmforcefields/pull/274 Scattered fixes to get CI running by @mattwthompson in https://github.com/openmm/openmmforcefields/pull/290 Docs Update docstrings, run in CI by @mattwthompson in https://github.com/openmm/openmmforcefields/pull/240 New Contributors @jthorton made their first contribution in https://github.com/openmm/openmmforcefields/pull/288 Full Changelog: https://github.com/openmm/openmmforcefields/compare/0.11.2...0.12.0