I found that rule that make nuclei with the same atomic number equivalent is very useful for me (described in 7.8.1 Generic Jastrow construction framework), but for term with rank [2,1] I want to set nuclei with the same atomic number equivalent and

1-Z1=2-Z1, 1-Z2=2-Z2 for all available nuclear numbers.

It gave me the following groups of parameters:

1-1-Z1

1-1-Z2

1-1-Z3

...

1-2-Z1

1-2-Z2

1-2-Z3

...

but if I add 1=2 rule or 1-1=1-2=2-2 to Z rule then I will get only:

1-1-Z1

1-1-Z2

1-1-Z3

terms.

I think that in this case it is not correct to consider the interaction of electrons with parallel and antiparallel spins equivalent.

**Could it possible to add rule 1-Z=2-Z that means 1-Z1=2-Z1, 1-Z2=2-Z2, ..... for all available nuclear numbers.**

Actually I wrote python script that create .casl file of arbitrary structure (that I want) for a large number of molecules automatically, but I think it's very useful to group nuclears on its numbers but consider the interaction of electrons with parallel and antiparallel spins separately and this new rule would be a more elegant way to do so.

P.S. It is not difficult to see that Z6 is not any carbon atom, but the 6th type of atoms in the molecule (in the defeat of their appearance in the list of atoms). I think that this is an even more natural way of numbering.

Best, Vladimir.