Update potentials.rst

docs/source/potentials.rst

@@ -128,16 +128,12 @@ where
 
  - 'Labels' are the parameter name,  for printing purposes only; 
  - 'n1', 'n2', 'n3', ... are the 'powers' of an expansion term, e.g. 
-
- .. math:: 
-
-    V(r_1,r_2,r_3,r_4,r_5, r_6) = \sum_{n_1,n_2,n_3,n_4,n_5,n_1} f_{n_1,n_2,n_3,n_4,n_5,n_1} \xi_1^{n_1} \xi_2^{n_2} \xi_3^{n_3} \xi_4^{n_4} \xi_5^{n_5} \xi_6^{n_6}
- 
- 
+   :math:`V(r_1,r_2,r_3,r_4,r_5, r_6) = \sum_{n_1,n_2,n_3,n_4,n_5,n_1} f_{n_1,n_2,n_3,n_4,n_5,n_1} \xi_1^{n_1} \xi_2^{n_2} \xi_3^{n_3} \xi_4^{n_4} \xi_5^{n_5} \xi_6^{n_6}`
   - 'Index' is a switch to indicate if the corresponding parameter was fitted or can be fitted, with no impact on any evaluations of the PEF values. 
   - 'Values' are the actual potential parameters. Their order is not important for this implementation as long as the corresponding powers are defined. 
 
 
+
 In case the definition of PEF requires also structural parameters, such as equilibrium bond lengths :math:`r_{\rm e}`\ , equilibrium inter-bond angles :math:`\alpha_{\rm e}`, Morse exponents :math:`a` etc., in the ``COEFF  Powers`` form these parameters should be listed exactly in the order expected by the  implemented of the PEF (similar to the ``COEFF LIST`` form), but with dummy "powers" columns so that their 'values' appear in the right column. For example: 
 ::