[Wien] force difference between LAPW and PAW method

[Laurence Marks]

Did you check the absolute cell size for the two - minimize the energy
w.r.t. size?

---
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
http://www.numis.northwestern.edu
Corrosion in 4D http://MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
On Jan 29, 2016 04:38, "Pavel Ondračka" <pavel.ondracka at email.cz> wrote:

> Laurence Marks píše v Pá 29. 01. 2016 v 04:22 -0600:
> > Did you check for lattice parameter changes? A relatively small
> > change for a single unit cell can translate to something larger.
> > Unfortunately you need a reference compound, which is not so simple
> > in your case. Perhaps test SiO2, TiO2 & a few simple similar
> > compounds with the PAW & Wien2k.
>
> Yeah, some difference in cell size or positions was one of my suspects.
> I usually use VESTA to read the structure file from PAW software, then
> output to cif and use cif2struct to convert to struct and I was
> suspecting that maybe somewhere in this process I lose precision.
> So I've actually written a small python script to convert it directly
> with full precision allowed by the struct format, however the result
> were almost identical.
> Regarding the test cases, we tested eg. with rutile (with one atom
> slightly displaced to induce some forces) and the result were
> comparable (few percent difference).
>
> Best regards
> Pavel Ondračka
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