[molpro-user] Re: CI singles from SCF reference - spin symmetry issue

[Dan Haxton]

Sorry about that; I was copying from a script.  Put
a negative sign in front of 1.12 or 1.14.

 -- Dan



> Hello,
>
> I am trying to perform a very simple calculation
> on NO_2^+ with version 2002.6 in which I include all
> single excitations from a (closed-shell) SCF
> reference configuration.  I would like to do this
> for all spin and spatial symmetries, not only those
> of the SCF reference configuration.  Here is my
> input, done in cs symmetry with two irreps.
>
>
>
>
> geomtyp=xyz
>
> geometry
>  3
>  myno2
>  n    0.0        0.0     0.0
>  o    0.0     1.12  0.01
>  o    0.0     1.14  0.01
> end
>
> basis=cc-pvtz
> gprint,orbital,civector;
>
> rhf;wf,22;occ,9,2
> ci;occ,9,2;nopair;wf,22,1,0;state,1
> ci;occ,9,2;nopair;wf,22,1,2;state,1
> ci;occ,9,2;nopair;wf,22,2,0;state,1
> ci;occ,9,2;nopair;wf,22,2,2;state,1
>
>
>
>
> ( I will be calculating excited states once I get
> this working. )  The program stops on the second
> ci calculation with the statement "SPIN SYMMETRY
> NOT POSSIBLE."  I may not get around this error by
> instead defining the entire orbital space as a
> reference space and using restrict, i.e.
>
> ci;occ,60,30;wf,22,1,2;restrict,0,1,10.1,11.1,12.1 ......
>
> because of the hard-wired restriction upon the
> number of active orbitals.  ("TOO MANY ACTIVE
> ORBITALS")  I also may not use the REF card, which,
> as far as I can tell, only allows one to input
> additional spatial symmetries, not spin symmetries.
>
> There must be a way to do this calculation, and I
> apologize if I have missed something obvious, but I
> cannot find any options in the molpro manual that
> seem like they would get this to work.  Any help
> would be very much appreciated!
>
> Dan Haxton
> Postdoctoral research associate, JILA, CU-Boulder
>
>
>
>
>
>
>
>
>
>