[Pw_forum] pwscf: constrained total magnetic moment

[German Samolyuk]

Dear Gabriele,

Thank you for your answer.
I use version 4.2.1 and the input I used works for this version. For
the 4.3.2 vesion the input should be as you mentioned
tot_magnetization = some_number;. The results obtained with both
version are the same.

The output from 4.2.1 version has value of "corresponding" magnetic
field which according to text is defined as (e_f_up-e_f_dn)/2 in
Rydbergs.
My question was if there is any way to estimate corresponding external
magnetic field?

 Thank you,

German


On Thu, Jan 5, 2012 at 5:50 AM, Gabriele Sclauzero
<gabriele.sclauzero at epfl.ch> wrote:
> Dear German,
>
>     have you checked the manuals? In the input description of PWscf I've
> found:
>
>                    'total':
>                             total magnetization is constrained by
>                             adding a penalty functional to the total energy:
>
>                             LAMBDA * SUM_{i} ( magnetization(i) -
> fixed_magnetization(i) )**2
>
>                             where the sum over i runs over the three
> components of
>                             the magnetization. Lambda is a real number (see
> below).
>                             Noncolinear case only. Use "tot_magnetization"
> for LSDA
>
> I think that, in order to fix the total magnetization in LSDA calculations
> (nspin=2), you should simply set the tot_magnetization parameter
> (two-Fermi-energies method) and not specify the constrained_magnetization
> keyword. Which version of QE are you using?
>
>
> HTH
>
> GS
>
>
> Il giorno 03/gen/2012, alle ore 20.10, German Samolyuk ha scritto:
>
> Dear all,
>
> I do self-consistent calculation of supercell with 135 Fe atoms with
> constrained magnetization.
>
> nspin = 2,
> fixed_magnetization(3) = 360.0,
> constrained_magnetization = 'total' ,
>
> The output value of magnetic field:
>
>   Magnetic field            =   0.0785401 Ry
>
>
> In order to make a rough estimation of corresponding magnetic field in
> Tesla I should divide this value by mu_B and difference between
> total magnetic moments of system with constrain and without it?
>
> Thank you
>
> German Samolyuk
> Oak Rigde National Laboratory
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>
> § Gabriele Sclauzero, EPFL SB ITP CSEA
>    PH H2 462, Station 3, CH-1015 Lausanne
>
>
>
>
>
>
>
>
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