Mysterious Symmetries

Hello All,

I have a problem that happened not only with ELK, but also with VASP/Phonopy, but as it nonetheless occurs in ELK too, I thought someone might recognize it and be able to help me with it.
I want to plot the phonon bandstructure of Si. The plot looks exactly the same as it looked with VASP/Phonopy (See attached picture). It does not, however correspond to either the actual bandstructure (See the other picture. Isabel Klett, Tobias Zier, Baerbel Rethfeld, Martin E. Garcia, and Eeuwe S. Zijlstra. Isostructural elemental crystals in the presence of hot carriers. Phys.Rev. B, 91:144303, 2015).
The traversed path is (Gamma, X, L, W, K, Gamma).
Symmetries which should not exist can clearly be seen at 0.5, 2.5 and 3.625, but otherwise, the plot shows striking similarities to the true bandstructure. I just can't seem to find any errors.

The elk.in file used was:

tasks
0
205
220

nrmtscf
4

! You can add notes to the INFO.OUT file using the "notes" block
notes

avec
5.13 5.13 0.00
5.13 0.00 5.13
0.00 5.13 5.13

! this is the relative path to the species files
sppath
'<species_folder>'</species_folder>

atoms
1 : nspecies
'Si.in' : spfname
2 : natoms; atposl below
0.0 0.0 0.0
0.25 0.25 0.25

ngridk
4 4 4

ngridq
4 4 4

plot1d
6 200
0.0 0.0 0.0
0.0 1.0 0.0
0.5 0.5 0.5
0.5 1.0 0.0
0.75 0.75 0.0
0.0 0.0 0.0

Can anyone help me with this problem?

Thanks in advance.

Last edit: Thilo Waldmann 2019-07-09

Ideal.png

bandplot.pdf

Lars Nordström - 2019-07-09

Dear Thilo,
You use the wrong k-path. Remember that the k-points under plot1d is given in reciprocal lattice vectors. So you go from Gamma (0,0,0) to another Gamma (0,1,0) centered in next BZ. The reciprocal lattice vectors are given in INFO.OUT and you have to express X as a linear combination of them ...
Good luck,
Lars