The ABINIT Users Mailing List ( CLOSED )

[Martin Fuchs <fuchs@fhi-berlin.mpg.de>]

Dear Javad,

just a comment on the Cr pseudopotential:

For spin-polarized systems, a partial core
density must be included. Smaller core
cutoff radii (=larger core density) should
give more realistic results (=closer to all
electron). See the chapter on Mn in the
tutorial distributed with the fhipp package.
For Cr rc=1 bohr should be o.k.

In the 3d elements also the shape of the
d pseudowavefunction (your DOS peaks come
from these?) is important (spin polarization
happens mainly close to the Cr sites?). For
soft TM potentials the pseudowfct. differs
a lot from the full potential one, e.g. its
maximum is shifted to larger r. Small
core radii are thus preferred, the
default rcut_d=2+x is too large, I'd
try as small as you can afford (smaller
rcut_d implies higher plane wave cutoff).
Again, see the tutorial on what to expect.

Best wishes,
Martin




Javad hashemifar wrote:

> Dear Abinit users
>
> I am a new user of abinit and interested to study the ferromagnetic
> properties of CrAs in zincblend structure. As you may have heard about
> it, a couple of years ago it was found that CrAs in semi stable
> zincblend structure shows half metallic ferromagnetic properties.
> As it is recommended for every pseudopotential calculation, at the
> start of my study I am checking the reliability of the available
> pseudopotentials by comparing the results of Abinit by a full
> potential package (Wien2k).
> Please find as an postscript attachment the result of my comparison
> between the spin resolved DOS of CrAs in Abinit and Wien2k. As it is
> clear in the figure, the obtained DOS by using the norm conserving
> pseudopotentials (available in FHI homepage) is considerable different
> to the DOS of Wien2k, specially in the down channel.
> But we found that after applying core correction the DOS of Abinit
> becomes much more similar to the DOS of Wien2k, however still there
> are some nontrivial differences. The splitting of up and down valence
> states in Wien2k is higher than Abinit. In order to remove this small
> (but important) difference, I modified some parameters (increasing
> number of kpoints, cutoff energy, and decreasing the core correction
> radius), but these modifications have almost no effect on DOS (please
> see the attached figure).
> I would appreciate if any body explain me what is the source of
> difference between DOS of Abinit and Wien2k.
>
> Thanks in advance
> Javad Hashemifar

--
Martin Fuchs
Phone:  +30 8413 4802           | Fritz-Haber-Institut der MPG
Fax:    +30 8413 4701           | Faradayweg 4-6
E-Mail: fuchs@fhi-berlin.mpg.de | D-14195 Berlin (Germany)

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