[Pw_forum] constrained_magnetization

[chu-chun fu]

Dear Lorenzo,

Thank you for your response. Maybe I was not clear enough in my previous 
email. My question is not to give occupation Z to atom X, but local M 
(magnetization) to atom X. My question actually  concerns the 'atomic' 
constrained magnetization option already implemented in PWscf (in 
particular version 4.0.3) by adding a 'penalty functional' as can be 
seen in the SUBROUTINE add_bfield,
Just wonder if we can only constrain the local magnetization of only one 
species instead of all the atoms to respective values as fixed in the input.

Thank you again in advance for your response

Chu Chun


Lorenzo Paulatto wrote:
> In data 02 giugno 2009 alle ore 14:58:15, chu-chun fu 
> <chuchun.fu at cea.fr> ha scritto:
>
>> Dear PWscf developers and users,
>>
>> I would like to know if there is any possibility to constrain the
>> magnitud of magnetic moment of only one type of atoms in a
>> 'multi-component' system, when using 'atomic 
>> constrained-magnetization' ?
>
> Dear Chu Chun,
> it looks to me like your question is a variant on the very popular 
> "how can I fix atom X to have occupation Z". Unluckily there is no 
> real solution to it, as in DFT (especially on a plane-wave basis set) 
> there is no straitforward way to say to which atom a certain electron 
> belongs.
>
> Possible solutions include LDA+U and constrained DFT, which require 
> some knowledge and practice to use correctly. the former is explained 
> in detail in M. Cococcioni's PhD thesis which you can find on sissa 
> web pages: <http://www.sissa.it/cm/phd.php>; I don't know if the 
> latter is officialy supported in QE.
>
> best regards
>
>
> --Lorenzo Paulatto
> SISSA  &  DEMOCRITOS (Trieste)
> phone: +39 040 3787 511
> skype: paulatz
> www:   http://people.sissa.it/~paulatto/
>
>     *** save italian brains ***
>  http://saveitalianbrains.wordpress.com/


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