Giovanni Pizzi <[email protected]> 于2020年6月3日周三 下午5:06写道： > > Dear Chaman, > > 1. Yes. Actually, the band paths are just conventions, and try to pass > through all points and lines that have some symmetry. > So, the “suggested” band paths depend a lot on the lattice (and actually > also, in some cases, on the space group, if you want to cover all > inequivalent lines, as we discuss in [1]). > > The band structure is not affected by the path you choose (but of course, by > choosing a different path, you’ll see different bands). > > 2. It’s up to you. The ones of wikipedia cover a more complete path, but in > many cases the relevant features (e.g. lowest conduction band, highest > valence band, …) might only appear for a given material along a subset of the > lines, so you can decide show show less paths if you know the material and > what you are doing. > If you are unsure, I suggest to use our seekpath tool at > https://www.materialscloud.org/work/tools/seekpath - this will also > standardise the cell and check the spacegroup symmetry, and e.g. distinguish > between hP1 and hP2 (the path that you/wikipedia report is for what we call > hP2; hP1 needs an additional segment K-H_2 that is for some space groups is > not equivalent to K-H; our paper [1] explains more about this). > > 3. I don’t know. In general they use a shorter path and this is OK. The only > thing that I’m not sure about is what is the U point for them, as this is not > a standard point for a hexagonal cell. I didn’t have the time to check the > paper to see if they say what U is. However, note that at U most bands do not > have extrema (only one band has a minimum). > > So my guess, now that I look better at it, they might be just refolding the > band structure and using the names of the letters from the cubic FCC lattice, > refolded on the hexagonal lattice, and this might explain the U point (that > exists in cF lattices). > > However, to confirm this, you will need to check the refolding and try to > reproduce the band structure, to know if this is the correct interpretation > (or check if they explain more in the paper).
I've learned that band-unfolding but not previously heard about refolding the band structure. If the problem / properties can be explained by unfolding method, why do the revert job which should make the results for difficult to explains. Any hints for this? Regards. > > Hope this helps, > Giovanni Pizzi > > > [1] Y. Hinuma, G. Pizzi, Y. Kumagai, F. Oba, I. Tanaka, Band structure > diagram paths based on crystallography, Comp. Mat. Sci. 128, 140 (2017). DOI: > 10.1016/j.commatsci.2016.10.015 > > > -- > Giovanni Pizzi > Theory and Simulation of Materials and MARVEL, EPFL > http://people.epfl.ch/giovanni.pizzi > http://nccr-marvel.ch/en/people/profile/giovanni-pizzi > > On 26 May 2020, at 17:15, Chaman Gupta <[email protected]> wrote: > > Hey everyone, > > I am trying to study the effect of pressure on the band structure of 'Si - > simple hexagonal (Phase V)', which is stable between 17 to 30 GPa (approx.) > > Here is a paper published in Nature > (https://www.nature.com/articles/s41586-020-2150-y), which has a figure with > the band structure of Hex-Si (image is attached). The image has the following > path " A - Gamma - M - U - L ". > > IMAGE 1 IS HERE > > When I looked for BZ1 and the path to take for a simple hexagonal structure, > I came across this link ( https://en.wikipedia.org/wiki/Brillouin_zone). It > mentions the path to be "Gamma - M - K - Gamma - A - L - H - A|L - M|K - H" > > My questions: > > 1. From what I understand, the path and symmetry points are dependent on the > type of lattice, and highly affect the band structure. Is this statement > right or wrong? > > 2. Which k-points/ High symmetry points/ BZ1/ path should I use for my band > structure calculation? > > 3. Is it possible, by any chance the author of this Nature paper, might have > used the wrong k-points? Or should I use what they have used? > > Thanks for the help. > > > Regards, > > Chaman Gupta > Graduate Research Student, Novosselov Research Group, UW > Graduate Research Student, Pauzauskie Research Group, UW > University of Washington Seattle, M.S. in Mechanical Engineering > IIT Kharagpur, B.Tech in Metallurgical and Materials Engineering > Linked In | Email | P: +1 (206) 383-3514 > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users -- Hongyi Zhao <[email protected]> _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
