fix the bug in tolerance

Author: qzhu2017

pyxtal/tolerance.py

@@ -28,7 +28,7 @@ def __init__(self, *tuples, prototype="atomic", factor=1.0):
             attrindex = 6
             self.radius_type = "covalent"
         elif prototype == "molecular":
-            attrindex = 7
+            attrindex = 6
             self.radius_type = "covalent"
             f *= 1.2
         elif prototype == "metallic":