[Wien] mBJ + SOC :: spin-orbit splitting reduction

[Peter Blaha]

Look into the UG (lapw0).
One can now not only specify a "shortcut" for a particular functional
(VXC_MBJ), but also Ex, Ec, Vx and Vc individually.
You can specify whatever you want for Ex and Ec, but Vx and Vc are the 
important parts.
I'm abroad and cannot check the exact syntax given in the UG.

Am 06.02.2015 um 17:25 schrieb Martin Gmitra:
> Dear Peter,
>
> Thanks for your answer. Could you please give me a starting hint how
> to couple mBJ with PBE correlation instead LDA (I do not see any
> "flag", needed code modification)?
>
> Best regards,
> Martin Gmitra
> Uni Regensburg
>
> On 2/6/15, Peter Blaha <pblaha at theochem.tuwien.ac.at> wrote:
>> Hi,
>>
>> Sorry, I have no idea what the SO splitting of those previous
>> calculations has been.
>>
>> In order to get an estimate, compare the partial charges of those
>> splitted states. If there is a slight change in hybridization with
>> slightly modified s,p,d character of the two atoms, it may explain the
>> modified SO splitting.
>>
>> I'm also not sure at all if the character of the bands using mBJ is
>> better than in PBE, in fact I doubt it a little bit.
>>
>> Eventually you could play with correlation, i.e. couple mBJ exchange
>> with PBE correlation instead of LDA.
>>
>> Am 05.02.2015 um 21:46 schrieb Martin Gmitra:
>>> Dear Wien2k developers,
>>>
>>> We are observing underestimating trend of spin-orbit coupling
>>> splittings of Gamma_{15} bands in zinc-blende semiconductors.
>>>
>>> For instance in GaAs, the Gamma_{15v} splits to Gamma_{8v} and
>>> Gamma_{7v} by the values of about 0.29 eV, while experiment gives 0.34
>>> eV. PBE calculations gives 0.32 eV. Similar one sees for Gamma_{15c}
>>> which splits due to spin-orbit to Gamma_{8c} and Gamma_{7c} where mBJ
>>> gives 0.156 eV and PBE 0.181 eV. This one can compare to 0.174 eV from
>>> GW+SOC calculations [PRL 96, 086405].
>>>
>>> In PRB 82, 205212 you present two implementations of mBJ, within
>>> Wien2k and VASP. Could you please provide information whether both the
>>> implementations provide the same spin-orbit splittings of Gamma_{15}
>>> states?
>>>
>>> In case they are the same, which part of the Becke-Johnson approach
>>> can be responsible for such a reduction?
>>>
>>> Best regards,
>>> Martin Gmitra
>>> Uni Regensburg
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>>
>> --
>> Peter Blaha
>> Inst.Materials Chemistry
>> TU Vienna
>> Getreidemarkt 9
>> A-1060 Vienna
>> Austria
>> +43-1-5880115671
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
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>>
>
>

-- 
Peter Blaha
Inst.Materials Chemistry
TU Vienna
Getreidemarkt 9
A-1060 Vienna
Austria
+43-1-5880115671