About "Config" keyword (fwd)
John Kerkines
jkerkin at cc.uoa.gr
Fri Sep 7 09:50:28 BST 2001
Dear Prof. Werner (and listmembers),
Thank you for your reply. This is not what I am asking though. I would
like to know how to correctly READ the CI vector when using CSFs. For
instance, in the example I have mentioned in my initial message (see
below), when using determinants I read:
++ - + 0.1704248
as "1a1(alpha)2a1(alpha)1b1(beta)1b2(alpha)".
When using CSFs, the same line is:
++ - + 0.2783026
This corresponds to one spin-adapted linear combination, isn't it?
Which one is it? And which one is, for instance:
"+- + + 0.0000000"?
Ioannis Kerkines
On Thu, 6 Sep 2001, H.-J. Werner wrote:
> Hi,
> one can only specify "orbital configurations", i.e., the occupancy
> for each orbital. The program will then generate all possible
> spin-adapted CSFs. It is not possible to use subsets of CSFs
> for a given orbital configuration. The input for your example
> would read
>
> select
> con,2,0,1,1
> con,0,2,1,1
> con,1,1,1,1
>
> but in fact this would generate all possible CSFs for 3Sig-.
>
> Note that determinants can only be used for CASSCF but not
> for selected MCSCF (the select card triggers the use of CSFs).
> Also note that the closed-shell (inactive) orbitals are not
> included on the con cards as shown above.
>
> Instead of the orbital occupation numbers, one can also
> specify the orbitals itself, see e.g.,
>
> testjobs/h2o_explicit.test
> testjobs/o3_explicit.test
>
> and the manual.
>
> H.-J. Werner
>
> >
> > Hello,
> >
> > I am really puzzled by the use of the "Config" keyword in CASSCF
> > calculations. It is supposed to work with CSFs instead of Slater
> > determinants. I cannot understand how to read the CI vector in the case of
> > CSFs. For example, a single point CASSCF (4,4) triplet sigma minus
> > calculation 1st with determinants and 2nd with CSFs produces the
> > following
> > output:
> >
> > CI vector
> > ---------
> >
> > 20 + + 0.8726238
> > 02 + + -0.3497846
> > -+ + + -0.1704248
> > ++ - + 0.1704248
> > ++ + - 0.1704248
> > +- + + -0.1704248
> >
> > TOTAL ENERGIES -1815.56889064
> >
> >
> > CI vector
> > ---------
> >
> > 20 + + 0.8726238
> > 02 + + -0.3497846
> > ++ - + 0.2783026
> > ++ + - 0.1967896
> > +- + + 0.0000000
> >
> > TOTAL ENERGIES -1815.56889064
> >
> >
> > I can easily understand why there is a difference in coefficients between
> > CSFs and determinants, but how does one read for instance "++ - +" in the
> > CSF case? How does one know to which spin-adapted linear combination does
> > it belong to? What is the convention, since "++ - +" is written in both
> > cases?
> >
> > Best Regards
> > Ioannis Kerkines
> >
> >
>
>
> --
> Prof. Hans-Joachim Werner
> Institute for Theoretical Chemistry
> University of Stuttgart
> Pfaffenwaldring 55
> D-70569 Stuttgart
> Tel: (0049) 711 / 685 4400
> Fax: (0049) 711 / 685 4442
> email: werner at theochem.uni-stuttgart.de
>
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