[Wien] Spin-orbit coupling effect on band gap energy with LDA and GGA-PBE
Yakup Boran
yakupboran06 at gmail.com
Thu May 16 21:59:52 CEST 2024
Dear Dr. Blaha,
1. Case: I get 4.85 eV for LDA and then MBJ without SO (4.77 eV with SO)
2. Case: I get 4.74 eV for PBE and then MBJ without SO (4.79 eV with SO)
In the 1. case band gap decreases with SO, but in the 2. case band gap
increases.
I use Emax=5 eV for both calculations.
As far as I know, for SO calculation Emax should be chosen carefully. I did
another calculation with Emax = 6eV.
This time, in both cases, the band gap increases with SO.
In literature, band gap decrease is expected with SO, but I get band gap
increase in my calculations.
My question is if there is something else should I check. Or how one can
explain the band gap increase?
Best regards.
On Sat, May 11, 2024 at 7:14 PM Peter Blaha <peter.blaha at tuwien.ac.at>
wrote:
> 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
>>> WWW: http://www.imc.tuwien.ac.at WIEN2k: http://www.wien2k.at
>>> -------------------------------------------------------------------------
>>>
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>>
>> _______________________________________________
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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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>
> _______________________________________________
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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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