[CP2K:3748] Cartesian vs. spherical Gaussians in Quickstep

[Ondrej Marsalek]

Dear Juerg,

I see, thank you for the explanation. It seems that this introduces a
small inconsistency with basis sets that are originally designed with
Cartesian Gaussians, like Pople, but I would imagine that the
influence is small, especially with DFT.

Unfortunately, this still does not resolve our original issue, which
is the following. We would like to get from CP2K the MO coefficients
together with the basis set information in order to convert them to a
format readable by some quantum chemistry programs for population
analysis. The Molden format seems to be a good start, but it does not
really matter as long as we have the data from CP2K.

The MO coefficients can be printed out from

CP2K_INPUT / FORCE_EVAL / DFT / PRINT / MO

which works fine. We get them with spherical Gaussians, which seems to
be the right thing. Plus, the CARTESIAN keyword has some undesirable
side effects. The basis set information, however, is somewhat
confusing. It is printed out by the BASIS_SET keyword in the section

CP2K_INPUT / FORCE_EVAL / SUBSYS / PRINT / KINDS

and what we get is Cartesian, with no option for spherical. The
printing is done by write_orb_basis_set in basis_set_types.F. Is there
a reason for this? I would expect sphericals because of what you said
as well as for consistency with the MO output. It seems that
orb_basis_set contains both representations, although I did not dare
dig too deep. Is there an easy way to print out the basis set in
spherical contracted Gaussians?

Thanks a lot for any help or clarification,
Ondrej


On Fri, Mar 16, 2012 at 07:55,  <hut... at pci.uzh.ch> wrote:
> Hi
>
> CP2K uses contracted spherical Gaussian functions. Internally,
> to calculate integrals, these functions are transformed into
> primitive Cartesian functions and then the integrals are transformed
> back.
>
> regards
>
> Juerg
>
> --------------------------------------------------------------
> Juerg Hutter                         Phone : ++41 44 635 4491
> Physical Chemistry Institute   FAX   : ++41 44 635 6838
> University of Zurich               E-mail:  hut... at pci.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> ---------------------------------------------------------------
>
> -----cp... at googlegroups.com wrote: -----
> To: cp... at googlegroups.com
> From: Ondrej Marsalek
> Sent by: cp... at googlegroups.com
> Date: 03/15/2012 11:18PM
> Subject: [CP2K:3746] Cartesian vs. spherical Gaussians in Quickstep
>
> Hi,
>
> I would like to understand under what circumstances Quickstep uses
> spherical Gaussians as opposed to Cartesian Gaussians. From reading
> the 2005 Quickstep paper, I was under the impression that it only ever
> uses Cartesians. However, from some recent confusion in the output of
> some jobs a brief look at the code (did not go too deep, yet) it seems
> that spherical Gaussians come into play as well. Before I bring
> specific input file which triggered this, could someone please give me
> some general information on this topic?
>
> Thanks a lot,
> Ondrej
>
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