Dear Maria, have a nice research day. Before trying an answer to your questions, a kind reminder of some posting guidelines:
Please always include you affiliation/granting institute. Present yourself politely, and insofar do not link to other forum/posts outside QE-users mailing lists; it's not neither nice nor common practice to do that. Now, regarding your questioning, high-simmetry points in reciprocal space are used becaused they best describe the simplest (and the shortest, as far as I remember) paths a travelling periodic wave (bloch solutions) can take to move out through the crystal; the precise location of those points depends on the space group the crystal structure shows. So if one study the Band structure at those high-simmetry points, bassically all the E-k relationship are determined for electrons in the material under study. On the computing side, bands.x produces a x-coordinate values sequence to map the k points path in the same order you have specified previously; so, if your set the following path for the Si primitive cell (as recommended in *Hinuma et al*, *Band structure diagram paths based on crystallography*, *https://arxiv.org/abs/1602.06402 <https://arxiv.org/abs/1602.06402>*, there are two different recommended k-paths for Si, not connected by shortest distances between the U and K points) K_POINTS crystal_b 0.0000000000 0.0000000000 0.0000000000 10 0.5000000000 0.0000000000 0.5000000000 10 0.6250000000 0.2500000000 0.6250000000 1 0.3750000000 0.3750000000 0.7500000000 10 0.0000000000 0.0000000000 0.0000000000 10 0.5000000000 0.5000000000 0.5000000000 10 0.5000000000 0.2500000000 0.7500000000 10 0.5000000000 0.0000000000 0.5000000000 1 bands.x will generate 10 intermediate k-points in between Gamma->X (Beginning of first path) 10 intermediate k-points in between X->U 1 k-point at U (End of first path) (When you plot, draw a thick vertical line at this point to make clear this is the end of the path and that there is no connection with the next point - K - also). 10 intermediate k-points in between K-->Gamma (Beginning of second path) 10 intermediate k-points in between Gamma->L 10 intermediate k-points in between L->W 10 intermediate k-points in between W->X 1 k-point at X (end of second path) That is, 62 k-points for the recommended paths Γ—X—U|K—Γ—L—W—X. By the way, the plot you show in physics.stackexchange.com uses a custom selected k-path. One can choose the k-path that best fits/likes oneself, but the recommended one is just enough. Citing the hinuma *et al* paper, the recommend k-path is the one that "*cover all special wavevector (k -vector) points and lines necessarily and sufficiently*". So you can see/copy/build the suggested k-points path for your different structures by uploading your *.cif/*.pw.in files in https://www.materialscloud.org/work/tools/seekpath Hope all of this helps. Best regards and happy holydays! *Professor Josué Clavijo, Ph.D.* *Christian, born again* *Assistant Professor* Universidad Nacional de Colombia Bogotá DC Facultad de Ciencias Departamento de Química 571-3165000 Ext. 14445 [email protected] [email protected]
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