[Pw_forum] Fractional magnetization

Gabriele Sclauzero sclauzer at sissa.it
Mon Apr 27 11:09:41 CEST 2009

Dear Lex

Lex Kemper wrote:
> Hello everyone,
> I have a question regarding constrained magnetization calculations. I 
> notice in the manual that both multiplicity and tot_magnetization are 
> integers. 

Because these are meant for calculations with fixed (integer) occupations, therefore you 
can have only integer total magnetization.

> However, systems are not always found in an integer spin 
> state. Furthermore, being able to specify a non-integer spin state is 
> useful for making systems converge to a particular desired solution.
> At the moment, the only way I can specify a non-integer spin state is 
> by using the nelec/nelup/neldw combination. 

That's not true, you can fix the total magnetization (and also some "local" magnetic 
moments or even angles in noncolinear calculations) if you use broadening in the 
occupations (smearing) and specify you constraints through constrained_magnetization 
keyword and related variables. Please have a look at the corresponding sections of the 
INPUT_PW manual.



> The manual says this is 
> obsolete though, and to use the other variables instead. Should (at 
> least one) of these be changed to a real instead of an integer?
> Thanks,
> Lex Kemper
> Department of Physics & QTP
> University of Florida
> _______________________________________________
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> Pw_forum at pwscf.org
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