molecular dipoles of charged molecules

[Axel]

hi teo,

On Oct 19, 7:48 pm, Laino Teodoro <teodor... at gmail.com> wrote:
> > hmmmm.... the organization of this part of the input is a
> > bitconfusing.
>
> > i would have either expected that you move them to the
> > CP2K_INPUT / FORCE_EVAL / DFT / PRINT / LOCALIZATION / LOCALIZE /
> > PRINT
> > block where the other wannier center related output is found or
> > - which makes even more sense to me - move those subsections
> > directly into LOCALIZATION and merge LOCALIZATION%LOCALIZE
> > into LOCALIZATION.
>
> Well.. it has a sense how it is organized at the moment.

sorry, but i fail to see the sense in having a LOCALIZE section
inside a LOCALIZATION section and having a PRINT section inside
LOCALIZE when LOCALIZATION is itself in a PRINT section.

to me it would seem _much_ more reasonable to have the LOCALIZE
section (w/o its PRINT section) directly located under DFT.
the reason being that it "processes" the wavefunction in a similar
spirit than SCF, SIC and other sections there.

then _all_ print keys would be located directly in the DFT%PRINT
section and the wannier cubes output would be alongside the density
cubes, the wannier centers alongside the dipole moments, molecular
states etc. etc.

this is much more what "ordinary users(tm)" would expect where to
find the respective flags.

[...]

> well.. even with the center of charge or center of mass the dipole
> will always depend
> on the shape of the molecule.. it's unavoidable..
> maybe the center of charge or of mass behaves better.. but anyway..
> as you said in the
> first message the problem is ill-defined..

yep. i've been sleeping about it and using the center of mass is
actually the most reasonable choice. basically, one can view those
molecular dipoles (or multipoles) as a part of a multipole expansion
of a molecule and that molecule would rotate around its center of
mass.

i'll change my VMD code accordingly (i've been using the geometrical
center for simplicity, as not all file formats provide reliable
information
about masses in VMD).

[...]

> > a bit surprised by the discrepancies and wanted to check with the
> > folks
> > here whether this was intentional or accidental.
>
> I would say more laziness... ;-)

that would be ok to me, so if nobody objects i'll try to modify
the calculation of the molecular dipoles accordingly.

cheers,
    axel.

> Teo