[molpro-user] How to read the CSFs in a MRCI calculation?

[José Cortés]

Dear molpro users

I have a question about the output of the CSFs in a mrci calculation.
As an example suppose the He2 molecule with the 6-311G basis,
where an active space of 4e,4o was chosen in the part of the casscf
calculation.
Such election leaves only two external orbitals. As I understand the
symbols
"/" and "\" concerning to relative spin couplings, which are related to the
t vectors
in the genealogical coupling scheme.

For example for the following configurations (which are in the output of
the MRCI calculation)

         Reference coefficients greater than 0.0000000
         ================================
         2200           0.9959538
         /\/\           0.0600897

         Coefficients of singly external configurations greater than
0.0000000
         ================================================
         /\\0   5.1    -0.0062116
         20\0   6.1    -0.0055316

the t vectors specified in the complete basis set would be like:
         220000
         /\/\00
         /\\0/0
         20\00/

However, my question arises in the doubly external configurations

        Coefficients of doubly external configurations greater than
0.0000
         ===========================================
         PAIR    I     J   ->   K     L     NP  SYM  REF     COEFFICIENTS
           4    2.1   2.1      5.1   5.1     1   1    1   -0.02645858
           1    1.1   1.1      5.1   5.1     1   1    1   -0.02035037
           4    2.1   2.1      6.1   6.1     1   1    1   -0.01367284
           9    3.1   3.1      5.1   5.1     1   1    1   -0.01342122

In this case, how the t-vectors should be specified for each one of the
configurations in the complete basis set?
How do I get in this case each one of the configurations?
I would appreciate any information you could give me about it.

Regards
José Jara
Universidad Nacional
Autónoma de México
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