AW: [Wien] magnetic calculation

[Gerhard Fecher]

This depends a little bit, I think a spin polarized calculation for Al will result always in a non ferromagnetic state. Its different if you go e.g. to 3d metalls were you may have a ferromagnetic result for Cr even Cr is not a ferromagnet. 
In some cases you do not find an anti-ferromagnetic groundstate if you start with a ferromagnetic alignment of the spins, there you may have to change the spin of some atoms (depending on the complexity of the problem) such that the scf will find the lower energy for the AFM state. For compunds I try usually all possibilities and then compare the total energies. (Check that the charge convergence is ok and not only the energy and don't use too small numbers of k-points, in ferro- ferri- or af magnetic cases you can check for example fast whether the increase of k-points causes large shifts of Ef or the moments in the case.scfm file.)

Actually, I prefer to do the experiment first and then check with the calculation, but thats a matter of taste and capabilities.

Ciao
Gerhard

-----Ursprüngliche Nachricht-----
Von: wien-bounces at zeus.theochem.tuwien.ac.at im Auftrag von li wf
Gesendet: Do 08.12.2005 12:23
An: wien at zeus.theochem.tuwien.ac.at
Betreff: [Wien] magnetic calculation
 
Dear wien users,

     i want to calculate the electronic structure and magnetism of a 
compounds whose magnetism is still unknown. i have a puzzle that if i take 
a spin polarized calculation and found that it is spin-polarized, can i say 
that this compounds is ferromagnetism? should i also take 
antiferromagnetism calculation and them compare the total energy of the 
two? if a compound is not ferromagnetism, will the spin polarized 
calculation always give a non-magnetism result?

    thank you very much.

    best regards,

   wane

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