reduce precision error in energies by subtracting reference energies …

…in float64 before converting to float32

torchmdnet/datasets/memdataset.py

@@ -240,11 +240,10 @@ def get(self, idx):
 
         props = {}
         if "y" in self.properties:
-            props["y"] = pt.tensor(self.y_mm[idx], dtype=pt.float32).view(
-                1, 1
-            )  # It would be better to use float64, but the trainer complains
+            y = self.y_mm[idx]
             if self.remove_ref_energy:
-                props["y"] -= self.compute_reference_energy(z)
+                y -= self.compute_reference_energy(z)
+            props["y"] = pt.tensor(y, dtype=pt.float32).view(1, 1)
         if "neg_dy" in self.properties:
             props["neg_dy"] = pt.tensor(self.neg_dy_mm[atoms], dtype=pt.float32)
         if "q" in self.properties: