Transfer chain IDs to OpenMM topology. (ParmEd#1310)

swails · Jun 9, 2023 · bf0790f · bf0790f
1 parent 6e7332a
commit bf0790f
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/parmed/structure.py b/parmed/structure.py
@@ -1672,22 +1672,22 @@ def topology(self):
             self.unchange()
 
         self._topology = top = app.Topology()
-        chain = top.addChain()
         try:
             last_chain = self.residues[0].chain
             last_residue = None
             last_omm_residue = None
         except IndexError:
             # Empty topology
             return self._topology
+        chain = top.addChain(id=last_chain)
         # Add the atoms
         for i, atom in enumerate(self.atoms):
             # See if we need to add a new residue
             if atom.residue is not last_residue:
                 # See if we need a new chain
                 if last_chain != atom.residue.chain:
                     last_chain = atom.residue.chain
-                    chain = top.addChain()
+                    chain = top.addChain(id=last_chain)
                 last_residue = atom.residue
                 last_omm_residue = top.addResidue(atom.residue.name, chain)
             try: