[Wien] about "c" in TB-mBJ for open structures

[Fabiana Da Pieve]

Thank you very much Dr. Tran for your answer.

Well, maybe the suggestion by Prof. Blaha about using the "c" from a
calculation on graphite was because graphite has, at least, the C
atoms, which are the backbones bonds in organic crystals, and it has a
layered structure, as organic crystals, but organic crystals are muh
more "open" structures.

Anyway, I will maybe give it a trial anyway, and report to the mailing
list. Maybe indeed nothing will really change in terms of the band
gap.

Thanks
Fabiana

2013/8/15, tran at theochem.tuwien.ac.at <tran at theochem.tuwien.ac.at>:
> Hi,
>
> The mBJ potential can certainly not be used for systems with infinite
> vacuum (e.g., isolated molecule, surface), but for open structures the
> results can (maybe) still be ok without fixing "c" to some value
> (I have not tried myself, but maybe there is already results in the
> literature on open structures). If the gaps that you obtained without
> fixing "c" are not completely wrong, then I do not see any reason
> to fix "c" from a previous calculation.
>
> Also, there is no reason to fix "c" to the one obtained with graphite
> and not another solid. The procedure you mentioned looks ok.
>
> F. Tran
>
> On Thu, 15 Aug 2013, Fabiana Da Pieve wrote:
>
>> Dear wien2k developers and users
>>
>> I am checking the performance of Tran-Blaha mBJ with respect to GW
>> (non self consistent, for the moment) for some organic crystals (quite
>> open structures). For some of them the improvement with respect to LDA
>> (my starting point for G0W0) is good, for some others it is still
>> pretty good but I would like to have a better result. Prof. Blaha
>> suggested sometime ago to use the "c" parameter from bulk graphite,
>> since the scf calculation  of the "c" parameter of TB-mBJ in suh open
>> structures could have not so much sense.
>>
>> I am using Wien2k_11.1. Could you please confirm that the procedure I
>> am going to use (reported here below) is correct ?
>> (I just want a confirmation of what I read in the manual for this
>> version at page 50,
>> or IF THERE IS SOMETHING MORE THAT I SHOULD DO and that I did not
>> catch from the manual).
>>
>> I will do a bulk calculation for graphite, then take the graphite.grr
>> file, copy it into the orgcrystal.grr ; then I will cancel  the
>> orgcrystal.in0_grr file and then I will run finally the mBJ self
>> consistent run. The value inside the .grr file (which will be indeed
>> the one corresponding to bulk graphite) will be read by the scf mBJ
>> run.
>>
>> (sorry to ask, but my contract finishes soon and I cannot allow myself
>> to do stupid errors...)
>>
>> Thank you very much
>> Fabiana
>>
>> VUB, Free University of Brussels
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