[Pw_forum] How to calculate magnetization density when SOC is on
Andrea Dal Corso
dalcorso at sissa.it
Mon Jan 17 14:42:30 CET 2011
It seems to me that the code is OK. The spin of bands with the same
energy at k and -k is opposite.
If you want only the spin and not the band ordering you can set
no_overlap=.true.
in the bands.x input.
HTH
Andrea
On Mon, 2011-01-17 at 22:34 +0900, soroush pakseresht wrote:
> Dear Andrea,
>
>
> No, I have no inversion symmetry in my system. So I expect the bands
> at k,up and -k,dn (up,dn:spin) to be the same due to the time reversal
> symmetry. Let me quote part of my results for spin component 1 (Mx):
>
>
> at k
> 0.013 -0.007 0.108 -0.114 -0.108 0.102 -0.047 0.032
> -0.073 0.094
> 0.250 -0.250 -0.250 0.250 -0.250 0.250 0.243 -0.246
> 0.085 -0.058
> -0.050 -0.015 -0.058 0.072 0.048 -0.015 -0.075 0.072
> 0.129 -0.110
> -0.237 0.215 -0.087 0.085 -0.245 0.248 -0.243 0.244
> 0.249 -0.249
>
>
> at -k
> -0.013 0.007 0.114 -0.108 -0.102 0.108 -0.032 0.047
> 0.073 -0.094
> 0.250 -0.250 -0.250 0.250 -0.250 0.250 0.246 -0.243
> 0.058 -0.085
> 0.015 0.050 -0.072 0.058 0.015 -0.048 -0.072 0.075
> 0.110 -0.129
> -0.215 0.237 -0.085 0.087 -0.248 0.245 -0.244 0.243
> 0.249 -0.249
>
>
> I am in particular interested in band #29. As you can see for both k
> and -k they are positive (0.129, 0.110). However, I just found the
> eigen-energies corresponding to band #29 and #30 are just reversed
> between k and -k:
>
>
> at k
> -18.403 -18.403 -18.394 -18.393 -15.427 -15.426 -15.415 -15.415
> -15.401 -15.401
> -6.240 -6.236 -5.303 -5.292 -3.535 -3.529 1.548 1.611
> 2.796 2.864
> 3.577 3.637 3.964 4.063 4.482 4.540 4.800 4.833
> 7.649 7.776
> 8.465 8.587 9.257 9.264 10.863 10.866 12.514 12.537
> 13.804 13.824
> at -k
> -18.403 -18.403 -18.393 -18.394 -15.426 -15.427 -15.415 -15.415
> -15.401 -15.401
> -6.236 -6.240 -5.292 -5.303 -3.529 -3.535 1.611 1.548
> 2.864 2.796
> 3.637 3.577 4.063 3.964 4.540 4.482 4.833 4.800
> 7.776 7.649
> 8.587 8.465 9.264 9.257 10.866 10.863 12.537 12.514
> 13.824 13.804
>
> As you see, in the former the respective energies of bands #29 and #30
> are 7.649 and 7.776. But for -k, they become 7.776 7.649.
> Apparently the ordering of bands at k and -k are not the same. So I
> guess my mistake was to compare Mx at k with Mx at -k for the same
> band numbers. Do you have any suggestion?
>
>
> Thanks,
>
>
>
>
> On Mon, Jan 17, 2011 at 10:08 PM, Andrea Dal Corso <dalcorso at sissa.it>
> wrote:
> 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
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Pw_forum mailing list
> > > > 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
> > > _______________________________________________
> > > Pw_forum mailing list
> > > Pw_forum at pwscf.org
> > > http://www.democritos.it/mailman/listinfo/pw_forum
> > --
> >
> > 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
> >
> >
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
> >
> >
> >
> > --
> > Soroush Pakseresht
> > Advanced Science Institute (RIKEN)
> > Saitama-Japan
> >
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> --
> 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
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
>
>
> --
> Soroush Pakseresht
> Advanced Science Institute (RIKEN)
> Saitama-Japan
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
--
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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