[Pw_forum] Pseudopotential Format

[Lilia Boeri]

dear Paolo,

thanks a lot for answering. I actually tried all the possible tests with 
atomic, and they work nicely (total energies of different atomic configuratons differ 
by less than 1d-4 Ry, wavefunctions look all right, as well as logarithmic 
derivatives). As I told you, also in the bulk properties the difference 
between the two codes are tiny, but there is some difference in the 1d 
projection of the density and potential. 
Is there a way to plot the potential with atomic ?
Best,
Lilia

On Thu, 27 Oct 2005, Paolo Giannozzi wrote:

> On Thursday 27 October 2005 14:27, Lilia Boeri wrote:
> 
> > I have been trying to convert a Li pseudopotential downloaded from
> > the ABINIT database (LDA TM pseudopotential generated with the 
> > FHI98 code) to PWSCF UPF format; I thought I had succeeded in the
> > conversion because the total energies and other properties (bulk 
> > modulus, phonon frequencies etc) were very similar in the two 
> > programs (the difference in total energies is of the order of 1mRy).
> > The problem is that when I looked at the scf potential in real space 
> > given by the two programs the shape was not the same... The 
> > difference is really in the ionic part, which means that the 
> > pseudopotential is not the same in the two calculations. 
> 
> I already heard complaints that the conversion to UPF of FHI98
> pseudopotentials occasionally doesn't work, in particular when the
> "nonlinear core correction" is present. In order to solve this problem, 
> one needs to know what is inside the FHI98 files (what is inside the 
> UPF format is documented in file upftools/UPF) and to modify the 
> converter accordingly. Since the reward-to-effort ratio of such 
> operation is unfavourable, I am afraid that this is not going 
> to happen anytime soon.
> 
> Before claiming that the PP is not correctly converted, however, 
> you should try to verify what you get in an atomic calculation:
> the atomic code should work with UPF files, if the radial grid 
> does not start from 0. If you can well reproduce one-electron levels
> and total energy differences on different atomic configurations,
> your PP does the job. The difference you observe may be due
> to something else (for instance, you are not really looking at the 
> same quantity)
> 
> Paolo
> -- 
> Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
> Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
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