[Pw_forum] How to calculate magnetization density when SOC is on

[Andrea Dal Corso]

Please provide more details. Is there inversion symmetry in your system?

Andrea

On Mon, 2011-01-17 at 21:13 +0900, soroush pakseresht wrote:
> Dear Andrea and Gabriele,
> 
> 
> First, let me thank both of you for your valuable comments and
> feedbacks. 
> As suggested by Andrea, I used bands.x with lsigma=.true. . It seems
> to be working. Now I can see the results for Mx, My and Mz components
> of magnetization. However, something seems to be wrong. The
> magnetization which I get for the same band but at k and -k are
> exactly the same. Due to the strong spin-orbit coupling, I am
> expecting that the direction of magnetization at k becomes opposite to
> that at -k. Is it due to some symmetry constraints, which I might have
> not turned off during the SCF and NSCF calculations? Any idea?
> 
> 
> Looking forward for your response,
> Saeed
> 
> On Mon, Jan 17, 2011 at 7:55 PM, Andrea Dal Corso <dalcorso at sissa.it>
> wrote:
>         
>         On Mon, 2011-01-17 at 11:48 +0100, Gabriele Sclauzero wrote:
>         > Hi Soroush
>         >
>         > On 01/15/2011 02:50 PM, soroush pakseresht wrote:
>         > > Hi everybody,
>         > >
>         > >
>         > > Can anybody tell me how I can calculate the magnetization
>         > > M=M(Mx,My,Mz) for a system with spin-orbit coupling.
>         >
>         > Usually the three components of the total non-collinear
>         magnetization
>         > are printed at the end of the calculation, e.g.
>         >
>         >      The total energy is the sum of the following terms:
>         >
>         >      one-electron contribution =   -90.33299784 Ry
>         >      hartree contribution      =    49.63924278 Ry
>         >      xc contribution           =   -28.28794844 Ry
>         >      ewald contribution        =    -0.25003496 Ry
>         >      smearing contrib. (-TS)   =    -0.00000505 Ry
>         >
>         >      total magnetization       =     0.00     0.00     0.11
>         Bohr
>         > mag/cell
>         >      absolute magnetization    =     0.11 Bohr mag/cell
>         >
>         >
>         >
>         > > I'd like to know the total value of Mx, My, Mz for each
>         band at a
>         > > given kpoint.
>         > >
>         >
>         
>         
>         You can use the program bands.x with the flag lsigma=.true. .
>         Please check INPUT_BANDS for more info.
>         
>         HTH
>         
>         Andrea
>         
>         
>         
>         > What you're asking for is somehow the magnetization carried
>         by the
>         > individual KS eigenstates. I think that for this you'll have
>         to modify
>         > the PWscf or PostProc code. For instance you could start
>         from pp.x and
>         > modify the option plot_num=7 by performing the integral of
>         the
>         > resulting spin-density over the whole unit cell (should be
>         the sum
>         > over the FFT components, perhaps multiplied by some
>         normalization
>         > factor).
>         > Maybe it's easier to implement this directly in PWscf. At
>         the moment
>         > the code first computes the total spin-density (which is the
>         sum over
>         > bands and k-points of the individual KS densities) in
>         sum_band.f90
>         > (search for 'domag') and then the magnetization by
>         integrating the
>         > components of the spin-density (see compute_magnetization in
>         > PW/electrons.f90). You can modify sum_band.f90 by adding a
>         call to a
>         > function analogous to compute_magnetization but for each
>         single KS
>         > state.
>         >
>         >
>         > HTH
>         >
>         > GS
>         >
>         > >
>         > >
>         > > Thanks
>         > >
>         > > --
>         > > Soroush Pakseresht
>         > > Advanced Science Institute (RIKEN)
>         > > Saitama-Japan
>         > >
>         > >
>         > >
>         > > _______________________________________________
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>         > > Pw_forum at pwscf.org
>         > > http://www.democritos.it/mailman/listinfo/pw_forum
>         > >
>         >
>         >
>         > --
>         >
>         > Gabriele Sclauzero, EPFL SB ITP CSEA
>         > PH H2 462, Station 3, CH-1015 Lausanne
>         > _______________________________________________
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>         --
>         
>         Andrea Dal Corso                    Tel. 0039-040-3787428
>         SISSA, Via Bonomea 265              Fax. 0039-040-3787249
>         I-34136 Trieste (Italy)             e-mail: dalcorso at sissa.it
>         
>         
>         
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> 
> 
> 
> -- 
> Soroush Pakseresht
> Advanced Science Institute (RIKEN)
> Saitama-Japan
> 
> 
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-- 
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Bonomea 265              Fax. 0039-040-3787249
I-34136 Trieste (Italy)             e-mail: dalcorso at sissa.it