Enhance Arkane level of theory identification and AEC validation logging

Updated the logic for determining the Arkane level of theory to provide logging regarding its source and integrated AEC validation when BAC is not used.

Key changes include:
- Added logging to identify if the Arkane level of theory was explicitly set or inferred from the composite method or single point level.
- Integrated a call to `check_arkane_aec` to verify atom energy corrections when `bac_type` is not specified.

Author: calvinp0

arc/main.py

@@ -41,7 +41,7 @@
 from arc.species.converter import str_to_xyz
 from arc.species.species import ARCSpecies
 from arc.statmech.adapter import StatmechEnum
-from arc.statmech.arkane import check_arkane_bacs
+from arc.statmech.arkane import check_arkane_aec, check_arkane_bacs
 from arc.utils.scale import determine_scaling_factors
 
 
@@ -1201,13 +1201,26 @@ def check_arkane_level_of_theory(self):
         """
         Check that the level of theory has AEC in Arkane.
         """
+        explicitly_set = self.arkane_level_of_theory is not None
         if self.arkane_level_of_theory is None:
             self.arkane_level_of_theory = self.composite_method if self.composite_method is not None \
                 else self.sp_level if self.sp_level is not None else None
         if self.arkane_level_of_theory is None:
             logger.warning('Could not determine a level of theory to be used for Arkane!')
-        elif self.bac_type is not None:
-            check_arkane_bacs(sp_level=self.arkane_level_of_theory, bac_type=self.bac_type, raise_error=self.compute_thermo)
+        else:
+            if explicitly_set:
+                source = ''
+            elif self.composite_method is not None:
+                source = ' (from composite method)'
+            else:
+                source = ' (from sp level)'
+            logger.info(f'Arkane level of theory:{source} {self.arkane_level_of_theory}')
+            if self.bac_type is not None:
+                check_arkane_bacs(sp_level=self.arkane_level_of_theory, bac_type=self.bac_type,
+                                  raise_error=self.compute_thermo)
+            else:
+                check_arkane_aec(sp_level=self.arkane_level_of_theory,
+                                 raise_error=self.compute_thermo)
 
     def backup_restart(self):
         """