Merge pull request #2206 from mzbush/fix-mpcd-test

Fix mpcd particle positions

Author: joaander

hoomd/mpcd/pytest/test_collide.py

@@ -139,7 +139,7 @@ def test_run(self, small_snap, simulation_factory, cls, init_args):
         "angmom_rigid", [[0, 0, 0, 0], [0, 2, 3, 4]], ids=["Nonrotating", "Rotating"]
     )
     @pytest.mark.parametrize(
-        "pos_rigid", [[0, 0, 0], [10, 10, 10]], ids=["center", "edge"]
+        "pos_rigid", [[0, 0, 0], [5, 5, 5]], ids=["center", "edge"]
     )
     @pytest.mark.parametrize(
         "def_rigid,properties_rigid",
@@ -208,6 +208,7 @@ def test_rigid_collide(
     ):
         if "kT" not in init_args:
             init_args["kT"] = 1.0
+        L = 11  # length of box
 
         N_mpcd = len(def_rigid["constituent_types"])
         rng = np.random.default_rng(seed=42)
@@ -216,7 +217,7 @@ def test_rigid_collide(
 
         # create simulation
         initial_snap = one_particle_snapshot_factory(
-            particle_types=["A", "B"], position=pos_rigid, L=21
+            particle_types=["A", "B"], position=pos_rigid, L=L
         )
         total_mass = properties_rigid["mass"][0]
         if initial_snap.communicator.rank == 0:
@@ -225,10 +226,13 @@ def test_rigid_collide(
             initial_snap.particles.velocity[:] = [velo_rigid]
             initial_snap.particles.angmom[:] = [angmom_rigid]
 
-            # place the mpcd particles on top of constituents
+            # place the mpcd particles on top of constituents, accounting for PBCs
+            positions = np.add(def_rigid["positions"], pos_rigid)
+            positions[positions < -L * 0.5] = positions[positions < -L * 0.5] + L
+            positions[positions > L * 0.5] = positions[positions > L * 0.5] - L
             initial_snap.mpcd.N = N_mpcd
             initial_snap.mpcd.types = ["C"]
-            initial_snap.mpcd.position[:] = def_rigid["positions"]
+            initial_snap.mpcd.position[:] = positions
             initial_snap.mpcd.velocity[:] = velo_mpcd
 
         sim = simulation_factory(initial_snap)
@@ -338,7 +342,7 @@ def test_rigid_collide_free(
         # create simulation
         total_mass = properties_rigid["mass"][0]
         initial_snap = two_particle_snapshot_factory(
-            particle_types=["A", "B", "C", "D"], L=21
+            particle_types=["A", "B", "C", "D"], L=11
         )
         if initial_snap.communicator.rank == 0:
             # put a free particle that doesn't participate in collision on top of