[Wien] metal or semiconductor

[Peter Blaha]

GGA+U affects only the position of the correlated electrons (3d band or 
4f, ..), but not of the delocalized states (eg. Ni-4s band in NiO)

Therefore you cannot get the correct gap in NiO with GGA+U, because the 
Ni-4s states limit the size of the gap, even when you split the d-band 
by an enormous U.

mBJ also affects the Ni-4s states and shift it up, so that the gap is 
correct.

On the other hand, for 4f systems, mBJ can be too "weak" to open a gap.

Since we do not know your compound, we cannot say anything concrete, 
but: yes, there is a possibility that GGA+U still gives a metal while 
mBJ gives a semiconductor.



Am 07.08.2019 um 19:39 schrieb Wien2k User:
> Dear Prof.Laurence Marks
> thank you very much for your reply
> 
> my scientific reasoning is the following;
> i noticed that mbj and GGA+U give almost the same band topology except 
> that mBJ caused a band shift that showed semiconductor behavior,
> i think that mBJ is better suited to describe band-gaps than GGA+U, i 
> think the material is semiconductor
> 
> I still have a confirmation or another explanation
> 
> Le mer. 7 août 2019 à 19:30, Laurence Marks <laurence.marks at gmail.com 
> <mailto:laurence.marks at gmail.com>> a écrit :
> 
>     A good question which nobody can answer for you. These questions are
>     why we do science.
> 
>     _____
>     Professor Laurence Marks
>     "Research is to see what everybody else has seen, and to think what
>     nobody else has thought", Albert Szent-Gyorgi
>     www.numis.northwestern.edu <http://www.numis.northwestern.edu>
> 
>     On Wed, Aug 7, 2019, 18:22 Wien2k User <wien2k.user at gmail.com
>     <mailto:wien2k.user at gmail.com>> wrote:
> 
>         Dear Wien2k users;
> 
> 
>         after GGA+U+SOC calculation,  I found that the studied material
>         is a metal ( even for a large value of Ueff ) but when I redid
>         another calculation with mBJ based on GGA+U+SOC
>         {mbj(GGA+U+SOC)}, I found a semiconductor.
> 
>         Which of these two behaviors is the most correct?
>         _______________________________________________
>         Wien mailing list
>         Wien at zeus.theochem.tuwien.ac.at
>         <mailto:Wien at zeus.theochem.tuwien.ac.at>
>         https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=8jjendLnW4pTRLRAFSiEHRNKc7Rm4mBZIWlP5bLHpyU&s=CY4MRCXzXg-Rf6vqAoruCrdbxKMgnjfD7ePlMpLIC4o&e=
>         SEARCH the MAILING-LIST at:
>         https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=8jjendLnW4pTRLRAFSiEHRNKc7Rm4mBZIWlP5bLHpyU&s=4s-Smpi_42mHR_QVgwhhOhF3L2KLfo7ZnEYxXx0q9ks&e=
> 
>     _______________________________________________
>     Wien mailing list
>     Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at>
>     http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>     SEARCH the MAILING-LIST at:
>     http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
> 
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
> 

-- 
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW: 
http://www.imc.tuwien.ac.at/tc_blaha-------------------------------------------------------------------------