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[Philippe Blaise <philippe.blaise@cea.fr>]

Dear Matteo,

we (me and Pierre-Yves Prodhomme during his thesis) have done some GW 
calculations using
some HGH pseudos one year ago, especially for Hf-based oxides.

May be, it's time to clarify the limitations of such an approach when 
using the GW functionalities of abinit ?

The first work around is to nullify the spin-orbit coupling terms in the 
hgh file.
In fact for our calculations, semi-core states have been proven useful, 
even without the SO term,
for DFT and GW calculations, and as far as I understand, by default the 
SO terms are not really used
(no spin orbit coupling).

Then, I remember also that we have had to modify some irrelevant tests 
in abinit, and to play
a little bit with the kssform keyword (probably we have set kssform = 0, 
but now it is obsolete).

I'm not totally confident with that, but anyway, at the end the results 
seemed to be quite correct,
by providing at least realistic band gaps, compared to other TM pseudos, 
i.e. without semicore states.

Also, I'm quite sure that we didn't use the

inclvkb

variable - in fact it seems to be undocumented, what is its exact meaning ?

Best regards,

Philippe

Matteo Giantomassi a écrit :
> > Dear Seungmi,
> >
> > I don't exactly if HGH pseudos are working in the GW code.
> >     
>
>  HGH pseudos contain additional projectors for the spin-orbit coupling term.
>  Since GW is not yet able to deal with non-collinear systems
>  HGH pseudos, at present, can only be used to generate a KSS file in the
>  collinear case employing kssform ==3
>
>  Please note however that, to the best of my knowledge, nobody has ever
> used HGH to perform
>  GW calculations. I ran some tests and indeed the code stops complaining
> about the number of
>  projectors found in the pseudopotential file.
>  Making the GW part work with HGH will require some change in the code as
> well as
>  additional testing. For the time being I suggest use "standard"
> norm-conserving pseudos
>  or the files available in the Goedecker-Teter-Hutter (GTH) table.
>
>  I agree with Fabien on the need of adding semicore states during the
> generation of the
>  pseudo. Please keep in mind, however, that an accurate
>  pseudo with semicore states would require more than one projector per
>  angular state. If you don't find the elements you need in the GTH table,
>  you might use the opium generator to have more than one projector per a
> particular l
>  (FHI doesn't support multiprojector pseudopotentials)
>
>  By the way:
>  As already explained in the forum, in case of pseudos with more than one
> projector per angular state,
>  the treatment of the non analytic behavior of the inverse dielectric
> matrix is not
>  coded. In this case one has to use inclvkb==0 during the screening run.
>
>  Hope it helps,
>  Best Regards,
>  Matteo Giantomassi
>
>
>   
> > But something I had repeated many times in this forum: when performing a
> > GW calculation, one should always choose a pseudopotential, which
> > considers the semicore states as valence. Here for indium, I think the
> > 4s4p4d should be treated as valence, else the exact-exchange operator
> > could be off by several eV.
> > Eventually, I advise you to create your own pseudo...
> >
> > Cheers,
> >
> > Fabien
> >     
>
>
>