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

[tran at theochem.tuwien.ac.at]

Are you using a wien2k version which is recent enough to allow keywords
(instead of numbers) in case.in0?

On Fri, 6 Feb 2015, Martin Gmitra wrote:

> 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
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>
>
> -- 
> Martin Gmitra
> Institute for Theoretical Physics
> University Regensburg
> 93040 Regensburg
> Germany
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