Added an error if no stress tensor is found

Author: mesonepigreco

Modules/Relax.py

@@ -609,6 +609,8 @@ def vc_relax(self, target_press = 0, static_bulk_modulus = 100,
                 if ensemble_loc is not None and self.save_ensemble:
                     self.minim.ensemble.save_bin(ensemble_loc, pop)
 
+
+
             self.minim.population = pop
             self.minim.init(delete_previous_data = False)
 
@@ -625,6 +627,11 @@ def vc_relax(self, target_press = 0, static_bulk_modulus = 100,
             stress_tensor *= sscha.SchaMinimizer.__RyBohr3_to_evA3__
             stress_err *=  sscha.SchaMinimizer.__RyBohr3_to_evA3__
 
+            # Check if the stress tensor is actually loaded in the ensemble
+            if np.max(np.abs(self.stresses)) < 1e-10:
+                # Probably there is an error in the submission of the stress tensor calculation
+                raise ValueError("Error, the stress tensor is not loaded in the ensemble. Check the stress tensor calculation.")
+
             # Get the pressure
             Press = np.trace(stress_tensor) / 3