diff --git a/mlcalcdriver/calculators/ase_calculators/asespkcalculator.py b/mlcalcdriver/calculators/ase_calculators/asespkcalculator.py
index 2d5ee1d..2344c23 100644
--- a/mlcalcdriver/calculators/ase_calculators/asespkcalculator.py
+++ b/mlcalcdriver/calculators/ase_calculators/asespkcalculator.py
@@ -7,12 +7,13 @@
 
 class AseSpkCalculator(Calculator):
 
-    def __init__(self, model_dir, available_properties=None, device="cpu", **kwargs):
+    def __init__(self, model_dir, available_properties=None, device="cpu", md=False, **kwargs):
         Calculator.__init__(self, **kwargs)
         self.schnetpackcalculator = SchnetPackCalculator(
             model_dir=model_dir,
             available_properties=available_properties,
             device=device,
+            md=md,
         )
         self.implemented_properties = self.schnetpackcalculator._get_available_properties()
         if "energy" in self.implemented_properties and "forces" not in self.implemented_properties:
diff --git a/mlcalcdriver/calculators/schnetpack.py b/mlcalcdriver/calculators/schnetpack.py
index b17848d..a5e3608 100644
--- a/mlcalcdriver/calculators/schnetpack.py
+++ b/mlcalcdriver/calculators/schnetpack.py
@@ -22,11 +22,7 @@ class SchnetPackCalculator(Calculator):
     """
 
     def __init__(
-        self,
-        model_dir,
-        available_properties=None,
-        device="cpu",
-        units=eVA,
+        self, model_dir, available_properties=None, device="cpu", units=eVA, md=False,
     ):
         r"""
         Parameters
@@ -47,6 +43,7 @@ def __init__(
             a SchnetPackCalculator.
         """
         self.device = device
+        self.md = md
         try:
             self.model = load_model(model_dir, map_location=self.device)
         except Exception:
@@ -65,6 +62,15 @@ def device(self):
     def device(self, device):
         self._device = str(device).lower()
 
+    @property
+    def md(self):
+        return self._md
+
+    @md.setter
+    def md(self, md):
+        assert isinstance(md, bool)
+        self._md = md
+
     def run(
         self, property, posinp=None, batch_size=128,
     ):
@@ -148,14 +154,20 @@ def run(
                     deriv2 = -1.0 * deriv2
                 pred.append({out_name: deriv2})
         predictions = {}
-        if derivative:
-            predictions[property] = np.concatenate(
-                [batch[out_name].cpu().detach().numpy() for batch in pred]
-            )
+        if self.md:
+            for p in ["energy", "forces"]:
+                predictions[p] = np.concatenate(
+                    [batch[p].cpu().detach().numpy() for batch in pred]
+                )
         else:
-            predictions[property] = np.concatenate(
-                [batch[init_property].cpu().detach().numpy() for batch in pred]
-            )
+            if derivative:
+                predictions[property] = np.concatenate(
+                    [batch[out_name].cpu().detach().numpy() for batch in pred]
+                )
+            else:
+                predictions[property] = np.concatenate(
+                    [batch[init_property].cpu().detach().numpy() for batch in pred]
+                )
         return predictions
 
     def _get_available_properties(self):
diff --git a/requirements_dev.txt b/requirements_dev.txt
index cc9db37..a71d208 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,17 +1,16 @@
-pip==21.2.4
+pip==21.3
 wheel==0.37.0
-black==21.9b0
-flake8==3.9.2
-numpy==1.21.2
+black==21.11b1
+flake8==4.0.1
+numpy==1.21.4
 torch==1.9.1
-torchvision==0.10.1
-twine==3.4.2
+twine==3.6.0
 pytest==6.2.5
-pytest-cov==2.12.1
+pytest-cov==3.0.0
 pytest-sugar==0.9.4
-coveralls==3.2.0
+coveralls==3.3.1
 ase==3.22.0
 git+https://github.com/atomistic-machine-learning/schnetpack.git
-sphinx==4.2.0
-sphinx-rtd-theme==0.5.2
+sphinx==4.3.1
+sphinx-rtd-theme==1.0.0
 git+https://github.com/crossnox/m2r@dev#egg=m2r