[Pw_forum] question about constrained magnetization
Cyrille Barreteau
cyrille.barreteau at cea.fr
Thu Dec 3 11:28:27 CET 2009
Gabriele Sclauzero wrote:
>Dear Cyrille,
>
>Cyrille Barreteau wrote:
>
>
>>Dear all,
>>
>>I want to perform a calculation using the penalization technique.
>>In an unconstrained scf calculation the input_magnetization(i) (i=1,ntyp)
>>variable contains the m/n initial value of atom of type i, and this
>>quantity should
>>obviously belong to [-1,1] interval.
>>To perform a constrained magnetization of "atomic type" I have to
>>set the variable constrained_magnetization='atomic' and the magnetization
>>will be the one given by input_magnetization(i).
>>Therefore now input_magnetization(i) is no longer m/n but m only.
>>However it seems that the range of input_magnetization has not been
>>modified and is still within [-1,1] interval.
>>If ever I set input_magnetization(i)>1 then the code automatically
>>replace it by 1 and I cannot explore values larger than 1.
>>
>>
>
>
>
Dear Gabriele,
With your quick fix now the input_magnetization is no longer the
magnetization m but m/n
as it is when there is no penalization. Therefore we avoid the problem
due to the [-1,1] interval
however this makes things a litlle "crooked" since the charge n is not
precisely now (the charge
inside the sphere does not integrate to the total charge per atom..).
However with a little of mental gymnastic we can manage to obtain what
we want:-)
thanks
cyrille
--
==================================================================
Cyrille Barreteau | phone : +33 (0)1 69 08 29 51
CEA Saclay | fax : +33 (0)1 69 08 84 46
DSM/IRAMIS/SPCSI | email cyrille.barreteau at cea.fr
Batiment 462 |
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>I see your problem, thanks for pointing it out. I think that as a quick fix you can try to
>substitute the following line in PW/add_bfield.f90
>
> m2(1:npol,na) = m_loc(1:npol,na) - mcons(1:npol,nt)
>
>with
>
> m2(1:npol,na) = m_loc(1:npol,na) - mcons(1:npol,nt)*r_loc(na)
>
>and recompile. In the CVS version it should be line 67 of the file, just after
> IF (i_cons==1) THEN
> ! i_cons = 1 means that the npol components of the magnetization
> ! are constrained, they are given in the input-file
>
>Please let me know if it works.
>
>
>Regards,
>
>GS
>
>
>
>
>>Is there a way to circumvent this problem?
>>For clarity I have added below a simple example illustrating my problem.
>>thanks in advance..
>>
>> cyrille
>>
>>
>>
>
>
>
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