[Wien] A question regarding magnetic/spin calculation in Wien2k please

[Fecher, Gerhard]

and not to forget, if the symmetry of the structure you use does not allow for antiferromagnetism then you will not find it.

NOTE: Symmetry is everything 

Ciao
Gerhard


====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]" im Auftrag von "Laurence Marks [L-marks at northwestern.edu]
Gesendet: Freitag, 9. März 2012 18:13
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] A question regarding magnetic/spin calculation in Wien2k    please

Actually.... I have come across several cases where I started with a
ferromagnetic state and it converged to non-magnetic or even
antiferromagnetic, or the opposite. It does take a long time for it to
change, so as Xavier says it is probably better to start from
different minima.

Note: the atomic positions can couple in to the spin-state, so you may
need to do a full minimization not just a single set of atomic
positions.

On Fri, Mar 9, 2012 at 10:12 AM, Rocquefelte
<Xavier.Rocquefelte at cnrs-imn.fr> wrote:
> If you start from a ferromagnetic situation, you will converge towards a
> ferromagnetic state (I never encounter other situations).
> However, it does not mean that you will find the global minimum in terms of
> magnetic structure.
> It simply means that you have converged the electronic density related to
> the ferromagnetic configuration of your system (It will be a local minimum -
> a metastable situation).
>
> To know which magnetic structure is the more stable, you should try
> different magnetic ordering, or at least one ferromagnetic situation and few
> antiferromagnetic situations (if possible). Then by comparing the total
> energy of the different situations you will see which one is the more
> stable.
>
> In the other hand, another way to estimate the magnetic interactions in a
> system is to estimate the magnetic exchange couplings, J(ij), using a
> mapping analysis (based on energy differences between different magnetic
> orders). It will give you the nature of the magnetic interaction in all
> directions and will help you to figure out what is the fundamental magnetic
> state of your system.
>
> Best Regards
>
> Xavier
>
>
>
> On 03/09/2012 04:55 PM, Qiwen YAO wrote:
>>
>> Dear all,
>> May I ask:
>>
>> is it correct to assume that the WIEN2k code will Optimizes the spin
>> structure of a stucture/cell in ground state if, I choose spin-polarized
>> calculation for the structure/cell from the beginning?
>>
>> What I mean is:
>> for a compound, I only suspecting that it is magnetic and I have to
>> include spin-polarization in the calculation, but I don't know wheather it
>> is ferromagnetic, perfect-antiferromagentic or canted antiferromagnetic or
>> even a mixed state of the magnetic status, so I would just do a
>> spin-polarized calculation (selecting all the atoms in the cell to be
>> spin-up from the beginning), then the resulting converged spin state would
>> be the loweset energy state of the compound? - if that is a yes then it i
>> s basically the case that, Wien2k sort it out itself and practically it
>> was an Optimized spin structure for the compound in the ground state?
>>
>> Thank you for your time.
>>
>> Kind regards,
>> Qiwen
>>
>> **********************************************************
>>
>> Dr QiWen YAO
>> JSPS Fellow
>> Multifunctional Materials Group
>> Optical and Electronic Materials Unit
>> Environment and Energy Materials Research Division
>>
>> National Institute for Materials Science
>>
>> 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
>> Phone: +81-29-851-3354, ext. no. 6482, Fax: +81-29-859-2501
>>
>> **********************************************************
>>
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>
>
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--
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi
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