Added new config variable and documentation for symmetry tolerance.

nomad/config.py

@@ -178,7 +178,14 @@ mail = NomadConfig(
 )
 
 normalize = NomadConfig(
-    system_classification_with_clusters_threshold=50
+    # The system size limit for running the dimensionality analysis. For very
+    # large systems the dimensionality analysis will get too expensive.
+    system_classification_with_clusters_threshold=50,
+    # Symmetry tolerane controls the precision used by spglib in order to find
+    # symmetries. The atoms are allowed to move 1/2*symmetry_tolerance from
+    # their symmetry positions in order for spglib to still detect symmetries.
+    # The unit is angstroms.
+    symmetry_tolerance=0.1
 )
 
 client = NomadConfig(

nomad/normalizing/system.py

@@ -312,10 +312,9 @@ class SystemNormalizer(SystemBasedNormalizer):
             None: The method should write symmetry variables
             to the backend which is member of this class.
         """
-        # Try to use Matid's symmetry analyzer to anlyze the ASE object.
-        # TODO: dts, find out what the symmetry_tol does.
+        # Try to use Matid's symmetry analyzer to analyze the ASE object.
         try:
-            symm = SymmetryAnalyzer(atoms, symmetry_tol=0.1)
+            symm = SymmetryAnalyzer(atoms, symmetry_tol=config.normalize.symmetry_tolerance)
 
             space_group_number = symm.get_space_group_number()