[molpro-user] Different CASSCF energies for XYZ and Z-matrix inputs

[Kirk Peterson]

Lorenzo,

could you send this attachment again to the list?  It didn't seem to  
make it with your earlier post.

-Kirk

On Feb 26, 2009, at 9:19 AM, Lorenzo Lodi wrote:

> I am using molpro 2006.1 to calculate energies of the water molecule.
>
> For Cs geometries I get different CASSCF energies if I specify the
> geometry in the Z-matrix format (letting molpro determine the symmetry
> group) or in the XYZ format (specifying the symmetry group by hand).
> I attach a sample input (input.Cs) that reproduces this behaviour.
> I chose a Cs geometry very close to a C2v one for later cross-checks.
>
> In the first case (XYZ format for the geometry specification) I get a
> CASSCF energy of -76.12413261 hartree. In the second run I use the
> Z-matrix format and I get -76.14722726 hartree. The RHF energy is the
> same in both cases, -76.02696984 hartree.
>
> On the other hand, if I do the calculation in C2v symmetry  
> (input.C2v) I
> get -76.14722726 in both cases, so the problem (if it is a problem…)
> seems to be in the combination Cs+XYZ.
>
> Can anyone tell me what the origin of this behaviour is?
>
> Lorenzo Lodi
> _______________________________________________
> Molpro-user mailing list
> Molpro-user at molpro.net
> http://www.molpro.net/mailman/listinfo/molpro-user