[Pw_forum] How to calculate magnetization density when SOC is on
soroush pakseresht
spakinform at gmail.com
Mon Jan 17 14:34:48 CET 2011
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
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> >
> >
> >
> >
> > --
> > 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
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>
--
Soroush Pakseresht
Advanced Science Institute (RIKEN)
Saitama-Japan
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