changed default to mayer

Signed-off-by: Nick Papior <[email protected]>

src/sisl/physics/densitymatrix.py

@@ -421,7 +421,7 @@ def _convert(M):
             f"{self.__class__.__name__}.mulliken only allows projection [orbital, atom]"
         )
 
-    def bond_order(self, method: str = "wiberg"):
+    def bond_order(self, method: str = "mayer"):
         r"""Bond-order calculation using various methods
 
         For ``method='wiberg'``, the bond-order is calculated as:
@@ -453,14 +453,18 @@ def bond_order(self, method: str = "wiberg"):
 
         Parameters
         ----------
-        method : {wiberg, mayer, bond+anti}[:spin]
+        method : {mayer, wiberg, bond+anti}[:spin]
             which method to calculate the bond-order with
         """
         method = method.lower()
 
-        what = "sum"
+        # split method to retrieve options
         m, *opts = method.split(":")
+
+        # only extract the summed density
+        what = "sum"
         if "spin" in opts:
+            # do this for each spin x, y, z
             what = "spin"
             del opts[opts.index("spin")]