Merge pull request #972 from openforcefield/from-openmm-cutoffs

Ensure electrostatics "cutoff" is set in `from_openmm`

.pre-commit-config.yaml

@@ -46,7 +46,7 @@ repos:
     exclude: openff/interchange/_version.py|setup.py
     args: ["--py310-plus"]
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.3.7
+  rev: v0.4.1
   hooks:
     - id: ruff
       args: ["check", "--select", "NPY"]

docs/releasehistory.md

@@ -11,6 +11,10 @@ Dates are given in YYYY-MM-DD format.
 
 Please note that all releases prior to a version 1.0.0 are considered pre-releases and many API changes will come before a stable release.
 
+## Current development
+
+* #972 Fixes a bug in which PME electrostatics "cutoffs" were not parsed in `from_openmm`.
+
 ## 0.3.26 - 2024-04-16
 
 * #952 Drops support for Python 3.9.

openff/interchange/_tests/unit_tests/interop/openmm/_import/test_import.py

@@ -176,6 +176,39 @@ def test_openmm_native_roundtrip_metadata(self, monkeypatch, sage):
             del off_atom_metadata["match_info"]
             assert roundtrip_atom.metadata == off_atom_metadata
 
+    def test_electrostatics_cutoff_not_ignored(self, monkeypatch, ethanol):
+        pytest.importorskip("openmmforcefields")
+
+        import openmm.app
+        import openmm.unit
+        from openmmforcefields.generators import GAFFTemplateGenerator
+
+        monkeypatch.setenv("INTERCHANGE_EXPERIMENTAL", "1")
+
+        topology = ethanol.to_topology()
+        topology.box_vectors = Quantity([4, 4, 4], "nanometer")
+
+        gaff = GAFFTemplateGenerator(molecules=ethanol)
+        force_field = openmm.app.ForceField()
+
+        force_field.registerTemplateGenerator(gaff.generator)
+
+        system = force_field.createSystem(
+            topology=topology.to_openmm(),
+            nonbondedMethod=openmm.app.PME,
+            nonbondedCutoff=1.2345 * openmm.unit.nanometer,
+        )
+
+        interchange = Interchange.from_openmm(
+            system=system,
+            topology=topology.to_openmm(),
+        )
+
+        assert interchange["Electrostatics"].cutoff.m_as(
+            unit.nanometer,
+        ) == pytest.approx(1.2345)
+        assert interchange["vdW"].cutoff.m_as(unit.nanometer) == pytest.approx(1.2345)
+
     @needs_gmx
     def test_fill_in_rigid_water_parameters(self, water_dimer, monkeypatch):
         import openmm.app

openff/interchange/interop/openmm/_import/_import.py

@@ -216,6 +216,7 @@ def _convert_nonbonded_force(
 
     if force.getNonbondedMethod() == 4:
         vdw.cutoff = force.getCutoffDistance()
+        electrostatics.cutoff = force.getCutoffDistance()
     else:
         raise UnsupportedImportError(
             f"Parsing a non-bonded force of type {type(force)} with {force.getNonbondedMethod()} not yet supported.",