[Wien] Spin-orbit coupling effect on band gap energy with LDA and GGA-PBE

Peter Blaha peter.blaha at tuwien.ac.at
Sat May 11 18:14:10 CEST 2024


Do you get identical gaps for:

LDA and then MBJ  (no SO)

PBE and then MBJ  (no SO)   ???

If you did everything right, there is no reason why adding SO at the end 
should give a different result.

Probably some other mistake ... ?


Am 11.05.2024 um 17:32 schrieb Yakup Boran:
> Dear Dr Blaha,
>
> I think I did not write clear enough.
>
> The calculation was done by following:
>
> 1. I did regular scf calculation with LDA
> 2. I added mBJ on it.
> 3. Then I added SOC.
>
> I repeated the same calculation with PBE.
>
>
> Thank you
>
> 11 May 2024 Cmt, saat 17:08 tarihinde Peter Blaha 
> <peter.blaha at tuwien.ac.at> şunu yazdı:
>
>     No.
>
>     These 2 calculations should be exactly the same.
>
>     What matters is only:    XC_MBJ
>
>     Everything in parenthesis is only a comment to give you a few
>     common options.
>
>
>     Am 11.05.2024 um 16:00 schrieb Yakup Boran:
>>     Dear Dr Blaha,
>>
>>     Thank you for your response.
>>
>>     ———————————
>>     case.in0 for LDA is
>>
>>     TOT XC_MBJ ( (XC_PBE,XC_PBESOL,XC_WC,XC_MBJ,XC_SCAN)
>>
>>      R2V IFFT (R2V)
>>
>>      30 30 48 2.00 1 NCON 9 # min IFFT-parameters, enhancement
>>     factor, iprint, NCON n
>>
>>     ——————————-
>>     Case.in0 for PBE
>>
>>     TOT XC_MBJ ( (XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_SCAN)
>>     R2V IFFT (R2V)
>>
>>     30 30 48 2.00 1 NCON 9 # min IFFT-parameters, enhancement factor,
>>     iprint, NCON n
>>
>>     ———————-
>>
>>     Best regards
>>
>>     11 May 2024 Cmt, saat 16:03 tarihinde Peter Blaha
>>     <peter.blaha at tuwien.ac.at> şunu yazdı:
>>
>>         I'm not quite sure I understand what you did.
>>
>>         You are always using   mBJ  (for VX), but how do you mix in
>>         LDA or PBE ?
>>
>>         By default we use LDA for VC, (and anything for EX and EC,
>>         since this is
>>         not important).
>>
>>         Usually, the choice of VC has only a small effect (as
>>         compared to VX).
>>
>>         Please show the 2 lines in case.in0
>>
>>
>>         Am 10.05.2024 um 15:56 schrieb Yakup Boran:
>>         > Dear Wien2K users,
>>         > I am running a calculation for a Bi-containing compound with a
>>         > tetragonal structure type. I used LDA with mBJ, and then,
>>         due to the
>>         > heavy Bi atom, I did the SOC calculation. The calculated
>>         band gap
>>         > energy with SOC is smaller than without SOC. I checked the
>>         literature,
>>         > and the band gap decrease is common for SOC calculation.
>>         However, if I
>>         > use PBE-GGA with mBJ (instead of LDA with mBJ), the band
>>         gap energy
>>         > with SOC is greater than without SOC, which is contrary to the
>>         > literature.
>>         >
>>         >  Is it possible that I get a band gap decrease with LDA
>>         while I get a
>>         > band gap increase with PBE-GGA when the SOC effect is taken
>>         into
>>         > consideration?
>>         >
>>         > Any response will be appreciated. 
>>         >
>>         > Best Regards
>>         >
>>         > Yakup Bran
>>         >
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>>         -- 
>>         -----------------------------------------------------------------------
>>         Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060
>>         Vienna
>>         Phone: +43-158801165300
>>         Email: peter.blaha at tuwien.ac.at
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>
>     -- 
>     -----------------------------------------------------------------------
>     Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
>     Phone: +43-158801165300
>     Email:peter.blaha at tuwien.ac.at           
>     WWW:http://www.imc.tuwien.ac.at       WIEN2k:http://www.wien2k.at
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-- 
-----------------------------------------------------------------------
Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-158801165300
Email:peter.blaha at tuwien.ac.at           
WWW:http://www.imc.tuwien.ac.at       WIEN2k:http://www.wien2k.at
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