Posted by Per Åke Malmqvist on January 20, 2009 at 18:21:15:
In Reply to: CSF expansions 2 posted by Willem Van den Heuvel on January 20, 2009 at 14:59:22:
Dear Willem,
I have checked and double-checked: The routines in the rassi programs do the right thing,
which is precisely as you have quoted below; this is exactly in accordance with
Shavitt as well.
This means that I gave the wrong sign earlier. I'm sorry,
PÅ
: where a and b represent alpha and beta spin. Both have spin S=1/2 and Ms=1/2. I have used the algorithm given by Shavitt in a Lecture Note on GUGA [1] and find, for Ms=1/2:
: uud = 1/sqrt(6) * ( -2|aab| + |aba| + |baa| )
: udu = 1/sqrt(2) * ( |aba| - |baa| ),
: so with opposite sign for uud but equal sign for udu.
: Which one is correct?
: ref: [1] I. Shavitt, in 'The Unitary Group', ed. J. Hinze, Lecture Notes in Chemistry 22, Springer-Verlag, Berlin, 1981, p.55.
:
: Best regards,
: Willem Van den Heuvel