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abinit / abipy

Open-source library for analyzing the results produced by ABINIT
http://abinit.github.io/abipy
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Bug of high symmetry lines ? #166

Closed tlsong closed 5 years ago

tlsong commented 5 years ago

When I test the example in the website:http://abinit.github.io/abipy/flow_gallery/run_phonons.html#sphx-glr-flow-gallery-run-phonons-py, I find that the high symmetry line of the phonon band structure of AlAs is different with the high symmetry line of the phonon band structure of AlAs from the website:https://www.materialsproject.org/materials/mp-2172/.
It seems that the right high symmetry line is Gamma-X-W-K-Gamma-L-U-W-L-K | U-X, which is followed the reference: Setyawan, W. & Curtarolo, S. High-throughput electronic band structure calculations: Challenges and tools. Computational Materials Science 49, 299 – 312 (2010) Is this a bug? How can I fix it?

This similar bug is also found in the example (band structure of Si) of the website :http://abinit.github.io/abipy/flow_gallery/run_ht_si_ebands.html#sphx-glr-flow-gallery-run-ht-si-ebands-py The version of abipy which I use is 0.5.0

gmatteo commented 5 years ago

Thanks for reporting the problem. It should be fixed in 7b9b18f

In FCC, K and U are connected by a point group rotation and indeed band structure energies at K and U are equal.

The logic used in AbiPy to find the k-labels from the lattice and the reduced coords takes into account symmetry operations (rotations and G-translations) so that K-points that are equivalent by symmetry receive the same label.

This symmetrization step, however, should not be used when the high-symmetry path contains symmetry equivalent points.

tlsong commented 5 years ago

Ok, thank you