[Wien] two mBJ questions

[tran at theochem.tuwien.ac.at]

Thanks. We were not aware of this mistake in Table 7.3.

On Tue, 24 Nov 2015, Pavel Ondračka wrote:

> tran at theochem.tuwien.ac.at píše v Út 24. 11. 2015 v 14:32 +0100:
>> Hi,
>> 
>> It seems that the LDA energy with the mBJ orbitals leads
>> to the correct stability ordering. This sounds interesting, but
>> is it for the right reason? In other words, is it because the shape
>> of
>> the mBJ orbitals is more correct than with LDA/PBE/hybrid?
>> It's probably difficult to answer to this question. Beside this, in
>> my
>> opinion, there is nothing wrong (technically or theoretically) in
>> using
>> the LDA energies calculated with mBJ orbitals.
>
> Thanks for the clarification.
>
>> It's possible to use the PBE energy instead of LDA for the energy.
>> If you are using a recent version of WIEN2k which uses keywords
>> in case.in0 to specify the functional, then you need to specify
>> this for PBE energy with mBJLDA for the potential:
>> EX_PBE EC_PBE VX_MBJ VC_LDA
>> 
> Thanks a lot, my Wien2k version is the latest one.
>> 
>> The mBJ parameters were calibrated such that the mBJLDA potential
>> reproduces at best the experimental band gaps. The energy was not
>> used at all in this procedure.
>> 
>> If my explanations are too complicated, then I will try to make
>> more clear.
>> 
>> F. Tran
>> 
> Your explanation is perfectly clear. I think I understand now what
> caused my confusion. IMHO there is a mistake in userguide on page 126,
> Table 7.3: XC shortcut-switches. It shows that alternative to XC_MBJ is
> EX_LDA EC_LDA VX_MBJ VC_MBJ.
>
> So when I tried to use PBE energy for the first time, I took the long
> notation for XC_MBJ from userguide and replaced LDA with PBE, except than I got an
> error: 'VXCLM2 - Correlation-potential calculation not supported for'
> - MBJ
> So I removed VC_MBJ, however I forgot to replace it with VC_LDA, I got
> some bogus results and that started my confussion.
>
> Thanks for clearing this up.
> Best regards
> Pavel Ondračka
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