[Wien] The calculated-error of the magnetic moment

[Torsten Andersen]

I don't think you can expect integers from any DFT code, and 1% 
deviation from what you expect is not much, and I would say it is 
acceptable unless changing it by a few percent will change the 
properties dramatically (say, from insulator to metal, for example).

Best regards,
Torsten Andersen.


ccmp at nju.edu.cn wrote:
> Dear Dr. Stefaan Cottenier 
> 
> Thank you very much for your reply.
> 
> I had done a calculation for a cuprate, which has 40 atoms in a unit cell. 
> 
> Since our result shows this cuprate is insulator, the spin magnetic moment MUST be an integer number of Bohr magnetons. However, our calculated spin magnetic moment in unit cell is 1.01 Bohr magnetons, not equal exactly to 1.00 Bohr magnetons.
> 
> Do you think this small difference (smaller than one percent) is usual and acceptable?
> 
> Best wish!
> 
> Xiangang
> 
> 
> 
>>>Who can tell me the usual and acceptable calculated-error of the magnetic
> 
> moment in unit
> 
>>>cell?
> 
> 
>>Hard to say. From experience, I would say that plus or minus 0.1 mu_B (per
>>atom) is in most cases a reasonable deviation (for "normally behaving"
>>materials: no strong correlations or other 'special' properties). But that
>>does not guarantee that this deviation applies to your specific case...
> 
> 
>>Stefaan
> 
> 
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-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/