[molpro-user] Atom in an electric field: why the error message?

[Phillip Price]

I am a new Molpro user.

It doesn't get much simpler than this: I'm trying to calculate atomic  
and molecular polarizabilities, by looking at either energies or  
dipoles as a function of field.  Oddly (to me) things seem to work  
fine with molecules that I have tried, but not with atoms. For  
example, hydrogen atom in an electric field:

geometry={H;}
hf

This works fine.

But:

geometry={H;}
dip,0.0,0.0,0.001
hf

This generates an error:
?ERROR: FINITE FIELD PERTURBATION OPERATOR DMZ NOT TOTALLY SYMMETRIC


I have also tried Li and O, with the same error.

If I try this with a hydrogen _molecule_ instead of a hydrogen _atom_,  
there's no problem: Molpro runs without error and generates sensible  
answers.

This makes me think that with an atom, Molpro expects spherical  
symmetry and generates an error when it doesn't find it, but with a  
molecule it doesn't expect symmetry anyway so there is no problem.   
But I don't actually know that that is the issue.  And more to the  
point, I have tried specifying symmetry (using SET,SYMMETRY=Z for  
example) with no success.

Can someone point me the right direction?  I would appreciate it.

By the way, I am running Molpro 2006.1, because that is what is  
available on my lab's mainframe. I can switch to a more recent version  
if I have to, if that is the problem.

Thanks in advance for any help.

Phil Price
Lawrence Berkeley National Laboratory