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

Peter Blaha peter.blaha at tuwien.ac.at
Wed Feb 25 14:01:40 CET 2026


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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