Ensure that molecule orientation remains fixed for MDI (#428)

* Ensure that molecule orientation remains fixed for MDI

* Fix MDI test

* Lint MDI files

* Update MDI error message

* Reformat mdi_server.py with black

qcengine/mdi_server.py

@@ -270,6 +270,11 @@ def send_energy(self) -> float:
         if not self.molecule_validated:
             raise Exception("MDI attempting to compute energy on an unvalidated molecule")
         self.run_energy()
+
+        # Confirm that the calculation completed successfully
+        if not hasattr(self.compute_return, "properties"):
+            raise Exception("MDI Calculation failed: \n\n" + str(self.compute_return.error.error_message))
+
         properties = self.compute_return.properties.dict()
         energy = properties["return_energy"]
         MDI_Send(energy, 1, MDI_DOUBLE, self.comm)
@@ -305,8 +310,11 @@ def send_forces(self) -> np.ndarray:
 
     # Respond to the SCF command
     def run_energy(self) -> None:
-
         if not self.energy_is_current:
+            """Ensure that the orientation of the molecule remains fixed"""
+            self.update_molecule("fix_com", True)
+            self.update_molecule("fix_orientation", True)
+
             """Run an energy calculation"""
             input = qcel.models.AtomicInput(
                 molecule=self.molecule, driver="gradient", model=self.model, keywords=self.keywords

qcengine/tests/test_mdi.py

@@ -64,7 +64,17 @@ def test_mdi_water():
 
     # Test the <FORCES command
     forces = engine.send_forces()
-    expected = [0.0, 0.0, 0.00073827952, 0.0, 0.020208584243, -0.00036913976, 0.0, -0.020208584243, -0.00036913976]
+    expected = [
+        -0.0000635769828,
+        0.0,
+        0.000735537025,
+        0.0000317884914,
+        0.0202085843,
+        -0.000367768513,
+        0.0000317884914,
+        -0.0202085843,
+        -0.000367768513,
+    ]
     assert compare_values(expected, forces, atol=1.0e-6)
 
     # Test the >MASSES command