[molpro-user] norm of internals in MRCI

[Dumitru SERGENTU]

Hello molproers,

At the end of an MRCI calculation there is a square printed with some
norms: sq norm of internals, singles and pairs. I see that the sq norm of
singles is actually the sq norm of singles with respect to the one of the
reference. For pairs, I see that it is the sq norm of the doubly excited
external configurations (of the uncontracted ones and not of the
internally contracted ones, if I am right :-) ) also with respect to the
one of the reference. Now, I have no clue what sq norm of internals means
or how it is calculated. I guessed that it could be actually the sq norm
of the internal configurations derived from anihilations + creations among
the valence inactive occupied orbitals and valence occupied ones. However,
if I do a CAS(4/4) + MRCI on He2 for instance, I do not get internal
coefficients but still there is a sq norm for internals.

I would be very thankful if someone can clarify to me what internals
actually means and how I get that sq norm,
Many thanks,
Sergentu Claudiu.