[Wien] Wien Digest, Vol 83, Issue 5

[Peter Blaha]

Onsite PBE0  or "full hybrids" (YS-PBE0) ?
Crystal uses "full PBE0" !

Check :qtl    you should find the orbital occupation (and compare it with crystal)
(mind any local rotation matrix !)

Also: PBE0 calculations depend often on the starting density. Did you perform a
standard GGA calculation first and starting PBE0 from the converged GGA ???

To get reliable and good calculations for such a system in "non-trivial". Every code
will return "some result" by "clicking on a button", but this is not elemental Si
where all codes get the same result and DFT is rather good, but special care
must be taken.

In any case, ALWAYS calculate at least the forces (-fc 1) and check if forces are
small, even when you don't want to relax the structure. If the forces are "big",
you have either made a msitake in converting Crystal --> wien2k, or you have got
a "different" electronic structure than the crystal code (See my comments at the very
beginning).

It is hard to guess without all details.....

Am 18.10.2012 22:51, schrieb xiao.jianping at bccms.uni-bremen.de:
> Dear Plaha,
>
> I have used spin polarized. It is high spin case of Fe2+. I have not tried
> LDA/GGA+U yet, but I have used PBE0, it gives also different values for
> the two Fe atoms. I did not relax the structure. As the structure is
> relaxed by the CRYSTAL code, I need to make comparison so I did not relax
> the structure in the current calculation.
>
> All the best
> Jianping
>
> /////////////////////
>
> Message: 33
> Date: Thu, 18 Oct 2012 16:56:49 +0200
> From: Peter Blaha <pblaha at theochem.tuwien.ac.at>
> Subject: Re: [Wien] EFG calculation
> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> Message-ID: <508018B1.6000508 at theochem.tuwien.ac.at>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Without knowing the details:
>
> I hope you did it spin-polarized ?
> And most likely you will have to use something like LDA+U for the Fe 3d
> states.
> did you relax the atomic positions ?
>
> An Fe2+ ion could have a substantial EFG if it is in a high-spin state.
>
>
> Am 18.10.2012 11:24, schrieb xiao.jianping at bccms.uni-bremen.de:
>> Dear Friends,
>>
>> I have a model of two Fe substitution for two Zn in the ZnO wurtzite
>> phase. The symmetry and charge of these two atoms are quite similar.
>> However, the calculated EFG values of the two Fe atoms in the same
>> structure are huge different, one is 2.39, but the other is -9.10. Do you
>> have any advices and explanation for these. Thanks very much!
>>
>>
>> All the best
>> Jianping
>
>
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>

-- 
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
-----------------------------------------