# [Wien] question on irrep (irreducible representation) calculation

Hi. I'm using WIEN2k_14.2 version and have probelm on irrep (irreducible representation) calculation.
My system is CeFe2Al10 with spacegroup #63 (Cmcm).
I implemented scf cycle, with spin-orbit coupling (init_lapw and initso_lapw) & spin non-polarized, and plotted band with bandpath Z-R-S-GAMMA-Z-T-Y-GAMMA. When I tried to ! compile irrep calculation by x -irrep -so -p command (I implemented with parallel job), some of the symmetric points-Z,R,T gives the result like below in case.outputirso_1 file

********************************************************************************

knum =  1    kname= Z
k = 0.000000 0.000000 0.500000

The point group is D2h
8 symmetry operations in  8 classes
Table 23   on page  39 in Koster  et al [7]
Table 31.4 on page 247 in Altmann et al [8]

E    C2    C2`   C2"    I   IC2   IC2`  IC2"
& nbsp;G1+   A1g   1     1     1 &! nbsp;   1     1     1     1     1
G2+   B3g   1    -1     1    -1     1    -1     1    -1
G3+   B1g   1     1    -1    -1     1     1    -1    -1
G4+   B2g   1    -1    -1     1     1    -1    -1     1
G1-   A1u   1     1     1     1    -1    -1    ! -1    -1
G2-   B3u   1    -1     1    -1    -1     1    -1     1
G3-   B1u   1     1    -1    -1    -1    -1     1     1
G4-   B2u   1    -1    -1     1    -1     1     1    -1
--------------------------------------------------------
G5+   E1/2g 2     0     0     0     2    ! ; 0     0     0
G5-   E1/2u 2     0     0     0    -2     0     0     0

labeling of IRs can change due to choice of
symmetry axes: G2 <-> G3 <-> G4

Non-symmorphic crystal and k-point at the BZ surface:
IR of the space group for this k-point cannot simpl! e
be expressed as IR of the corresponding point group
times a phase factor, since exp(-i*k(Ri*tj-tj)) not 1
for all pair of {Ri|ti} and {Rj|tj}.

WILL BE IMPLEMENTED

********* **************************************************************! *********

When I take GAMMA-Y-F0-S-GAMMA-Z-T-G0-R-Z bandpath, there was no result like this one in R,Z,T point. I wonder why I have this kind of result in certain bandpath (Z-R-S-GAMMA-Z-T-Y-GAMMA) although the parity or irrep result implemented on symmetric point shouldn't depend on the bandpath. Isn't the latest version of WIEN2k can't implement irrep calculation on Non-symmorphic crystal? Is this structre non-symmorphic crystal? Importantly, why this discrepancy in irrep result happens between two different bandpaths?

Many thanks!

Nam

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