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

Kirk Peterson kipeters at wsu.edu
Sun Mar 1 17:44:09 GMT 2009


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


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
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