[Wien] Total (MT+interstitial) up/dn charge density with SOC?

Lukasz Plucinski lukasz.galaxy.s3 at gmail.com
Fri Feb 27 15:23:54 CET 2026


Dear Prof. Blaha,
Thank you for the answer.
Unfortunately, I still have an issue understanding this. I tried to analyze
the 12 operations, and it seems (correct me if I am wrong) some of them are
vertical mirror planes. However, this CrSb phase cannot have a vertical
mirror plane with SOC and M=001 (out of plane Neel), because any vertical
mirror would flip the moment of Cr1 spin (axial vector). The Cr2 atom is at
another height (another z position), so the mirror cannot swap Cr1 into Cr2.
Could you comment?
Best,
Lukasz

PS: In case you are rewriting the qtl code: would it be possible to print
out the relative phases of angular components? I know that the LAPW wave
function is quite complex, but perhaps phases (complex amplitudes) can
still be useful. I have been plotting real space densities with phases (see
Fig. 4 here: https://journals.aps.org/prb/abstract/10.1103/vcgr-qjyy) and
often it is quite clear which hydrogen-like orbitals participate and how is
their phase relationship.



On Wed, Feb 25, 2026 at 2:01 PM Peter Blaha <peter.blaha at tuwien.ac.at>
wrote:

> I don't think there is a problem with symmetso.
>
> CrSb with AF-structure for Cr reduces the 24 symops to 12.
> In this hexagonal lattice, the 2 Sb atoms are connected via inversion
> symmetry.
>
> Considering SO in 001 direction does not change this. And this is
> definitely ok. (due to hex symmetry you already have a preferred
> direction and SO in 001 does not change this.
>
> 100 direction, however, make a and b directions inequivalent and
> symmetry is reduced. Inversion is still kept, thus the 2 Sb atoms remain
> equivalent.
>
> Am 24.02.2026 um 17:28 schrieb Lukasz Plucinski:
> > Dear Prof. Blaha,
> > Thank you again for the quick response.
> > The particular case is with CrSb (NiAs lattice) and M=001.
> > 1. Cr and Sb atoms connected: space group 194, 24 symmetry operations
> > 2. Disconnect Cr atoms into Cr1 and Cr2: space group 164, 12 symmetry
> > operations
> > *3. init_so_lapw with M=001: 12 symmetry operations remain (but I think
> > only 6 should remain)*
> > 4. init_so_lapw with M=100: 4 symmetry operations remain
> > I might be doing something wrong, but this is how things work for me
> > with automatic scripts. I can provide the case.struct if needed for
> testing.
> > Best,
> > Lukasz
> >
> >
> > On Tue, Feb 24, 2026 at 3:28 PM Peter Blaha <peter.blaha at tuwien.ac.at
> > <mailto:peter.blaha at tuwien.ac.at>> wrote:
> >
> >     I don't know what you mean by: "the reduction of symmetries (due to
> SOC)
> >     did not work properly "  ???  Specific example, not just "feelings".
> >
> >     You can always put your symmetry "by hand" into case.struct, but
> >     i) make sure you do not put (or keep) symmetries, which are not
> present.
> >     ii) eventually, you need to split equivalent positions, if the
> >     corresponding sym.op was removed
> >     iii) The symmetry operations in case.struct, however, must also match
> >     conditions for the local rotation matrix AND the LM list in case.in2.
> >     You CANNOT remove some sym.ops and keep case.in2 the same.
> >
> >     The k-mesh follows automatically from the symmetry operations in your
> >     struct file (and inversion is added, unless -so is specified).
> >
> >     Please note: When comparing total energies with different
> magnetization
> >     directions in case.inso, it is strongly recommended to use a "common
> >     symmetry" (eventually P1 or P-1) with identical number of
> inequivalent
> >     atoms.
> >
> >     So test init_so with ALL magn.directions (always using the original
> >     struct file) and compare the symmetries. Then decide on a common
> >     symmetry.
> >
> >     A possible "trick" is always to displace an atom or change a,b,c a
> bit
> >     until you get the desired symmetry. After init_lapw, change the
> >     positions or a,b,c back to the original values (but do not run
> >     init_lapw
> >     again).
> >
> >
> >
> >      > instgen_lapw -ask
> >      > init_lapw -b -sp -prec 1 ...
> >      > init_so_lapw
> >      > runsp -so -p -ec ... -cc ...
> >      >
> >      > In the init_so_lapw script I can choose the magnetization
> >     quantization
> >      > axis (which becomes the Neel vector) and then symmetso
> automatically
> >      > reduces the symmetries (if needed) and creates the new
> >     case.struct and
> >      > then a proper klist for SOC.
> >      >
> >      > Sometimes I have a feeling that the reduction of symmetries (due
> >     to SOC)
> >      > did not work properly (for example it was not reduced, even if I
> >     might
> >      > expect some reduction). I would then like to reduce the
> >     symmetries by
> >      > hand (they are listed in the case.struct file). Is there a way to
> >     reduce
> >      > symmetries "by hand" in the case.struct and still run the
> >     calculation
> >      > properly (with reduced symmetries and adequate klist)?
> >      >
> >      > Best,
> >      > Lukasz
> >      >
> >      >
> >      >
> >      >
> >      > On Fri, Feb 20, 2026 at 7:32 PM Peter Blaha
> >     <peter.blaha at tuwien.ac.at <mailto:peter.blaha at tuwien.ac.at>
> >      > <mailto:peter.blaha at tuwien.ac.at
> >     <mailto:peter.blaha at tuwien.ac.at>>> wrote:
> >      >
> >      >     There is a file  case.normsoup/dn.
> >      >     It contains the up/dn charges for each eigenvalue after x
> >     lapwso -up.
> >      >
> >      >     In the next version,   x qtl -so -up   will provide a
> >     case.qtlup/dn
> >      >     file, where the last column contains the total up (dn) charge.
> >      >
> >      >     Of course, the interstital may contain spin-polarization, but
> >     usually
> >      >     this will be small as compared to the spin-polarization of
> >     the atoms.
> >      >
> >      >
> >      >     Am 20.02.2026 um 10:31 schrieb Lukasz Plucinski:
> >      >      > Dear All,
> >      >      >
> >      >      > I often use qtl to calculate "fat bands". With SOC this
> >     allows to
> >      >      > attribute spin-polarization to bands, in spaghetti plots.
> >      >      >
> >      >      > I understand that both qtl and lapw2 only operate on charge
> >      >     within MTs.
> >      >      > Is there any way to get total charge per E(k) eigenvalue,
> that
> >      >     means a
> >      >      > sum of MT and interstitial? Of course then there is no
> >      >      > orbital character, but just for spin it should not matter.
> >      >      >
> >      >      > lapw5 can plot real space charge densities, so it seems the
> >      >     information
> >      >      > is there.
> >      >      >
> >      >      > I ask because I think in some materials interstitial spin
> for
> >      >     E(k) may
> >      >      > not be negligible and it would be useful if WIEN2k can
> >     plot it.
> >      >      >
> >      >      > Best,
> >      >      > Lukasz
> >      >      >
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>  -----------------------------------------------------------------------
> >      >     Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060
> >     Vienna
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>  -----------------------------------------------------------------------
> >     Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
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> --
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> Email: peter.blaha at tuwien.ac.at
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