diff --git a/arkane/ess/molpro.py b/arkane/ess/molpro.py
index 35fcfbb00c..b891349483 100644
--- a/arkane/ess/molpro.py
+++ b/arkane/ess/molpro.py
@@ -435,10 +435,10 @@ def load_negative_frequency(self):
         if len(freqs) == 1:
             return -float(freqs[0])
         elif len(freqs) > 1:
-            logging.info('More than one imaginary frequency in Molpro output file {0}.'.format(self.path))
+            logging.info(f'More than one imaginary frequency in Molpro output file {self.path}.')
             return -float(freqs[0])
         else:
-            raise LogError('Unable to find imaginary frequency in Molpro output file {0}'.format(self.path))
+            raise LogError(f'Unable to find imaginary frequency in Molpro output file {self.path}')
 
     def load_scan_energies(self):
         """
@@ -458,7 +458,8 @@ def get_T1_diagnostic(self):
             if 'T1 diagnostic:  ' in line:
                 items = line.split()
                 return float(items[-1])
-        raise LogError('Unable to find T1 diagnostic in energy file: {0}'.format(self.path))
+        logging.warning(f'Unable to find T1 diagnostic in energy file: {self.path}')
+        return None
 
     def get_D1_diagnostic(self):
         """
@@ -472,7 +473,8 @@ def get_D1_diagnostic(self):
             if 'D1 diagnostic:  ' in line:
                 items = line.split()
                 return float(items[-1])
-        raise LogError('Unable to find D1 diagnostic in energy file: {0}'.format(self.path))
+        logging.warning(f'Unable to find D1 diagnostic in energy file: {self.path}')
+        return None
 
     def load_scan_pivot_atoms(self):
         """Not implemented for Molpro"""