bug in metadynamics parsing

Author: svandenhaute

psiflow/sampling/metadynamics.py

@@ -26,9 +26,9 @@ def __init__(
         _plumed_input = remove_comments_printflush(plumed_input)
         assert "METAD" in _plumed_input
         if "RESTART" not in _plumed_input:
-            _plumed_input = "RESTART\n" + _plumed_input
+            _plumed_input = "\nRESTART\n" + _plumed_input
         if "FLUSH" not in _plumed_input:  # add at the end!
-            _plumed_input = _plumed_input + "FLUSH STRIDE=1\nPRINT"
+            _plumed_input = _plumed_input + "\nFLUSH STRIDE=1\nPRINT"
 
         # PLUMED + WQ cannot deal with nonexisting hills files!
         if type(external) in [str, Path]:

tests/test_sampling.py

@@ -448,6 +448,7 @@ def test_order_parameter(dataset):
     state = simulation_output.state.result()
     CV = state.order["CV"]
     assert state.energy is None
+    assert np.all(np.isnan(state.per_atom.forces))
     assert np.allclose(CV, np.linalg.det(dataset[3].result().cell))
 
     # test batch evaluation of order parameter