[molpro-user] How to read the CSFs in a MRCI calculation?
José Cortés
zolidus at gmail.com
Thu Aug 20 09:32:01 BST 2015
Dear Professor Knizia
Thank you very much for your reply. I have a question concerning the
coefficients of
the doubly external configurations.
My aim is obtain the CI vector in terms of determinants. I know this can
not be done
directly in the mrci module of Molpro, so I wrote a perl script.
I have no problems in the case of the reference function and simple
external configurations.
I can go from CSF to determinants by the genealogical coupling scheme.
However, this
is more difficult in the doubly external configurations case.
First, i transform each contracted configuration in terms of uncontracted
CSF´s
\Psi_{ijp}^{ab}=\frac{1}{2}(\hat{E}_{ai,bj}+p\hat{E}_{bi,aj})\Psi_{0}
=\sum_{P\nu}<\Psi_{ijp}^{ab}|\Psi_{P\nu}^{ab}>\Psi_{P\nu}^{ab}
where \Psi_{0} is the reference function (p=1 singlet coupling, p=-1
triplet coupling).
Then, I multiply each uncontracted CSF by the associated coefficient with
\Psi_{ijp}^{ab}
(listed in the output). Later I express each uncontracted CSF in terms of
determinants.
As I understand it, the labels i, j, a, b, p in \Psi_{ijp}^{ab} refer to
"I J -> K L NP" in the output of Molpro.
However, performing this procedure does not achieve a square norm that
matches the output
CLASS SQ.NORM ECORR1 ECORR2
+++++++++++++++++++++++++++++++++++++++++++++++++++
Internals 0.00001717 0.00000000 -0.00000069
Singles 0.00065315 -0.00263386 -0.00263924
Pairs * 0.00787253* -0.03783725 -0.03783119
I do not understand that I'm doing wrong.
Perhaps, the coefficients associated with \Psi_{ijp}^{ab} are refer to a
non-orthonormal basis?
I would appreciate any help that you could provide me.
regards
Jose Jara
Universidad Nacional
Autónoma de México
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