In this paper, they have plotted the band structure of orthorhombic $\ce{CsPbI3}$ using Wein2k. The k-path given here is Γ—X—R—Z—Γ—X—R—A—M—X, but I cannot find the M point in the orthorhombic crystal structure online.

What is the M point of an orthorhombic crystal structure? What are the coordinates?

This question has reference to my previous post on the Brilloiun zone k-path.


1 Answer 1


This is not a direct answer to your question, but instead the description of a resource that you can use to learn about high symmetry points and paths of any structure (including your orthorhombic lead halide perovskite).

Website: SeeK-path

Short description: it allows you to upload a crystal structure (in many formats, including QE, VASP, CASTEP, cif), and it depicts the Brillouin zone, high symmetry coordinates and labels, and provides a suggested high symmetry path along the Brillouin zone on which to evaluate the band structure.

For you: if you upload your structure file (I understand you have it in QE format?), then it should provide the coordinates of the M point.

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    $\begingroup$ Thank you for your response @ProfM but Seek-path is not showing the M point as a high symmetry point of an orthorhombic crystal structure. However, this paper : doi.org/10.1016/j.jallcom.2020.158442 and the one I mentioned in my post have used "M" as one of the high symmetry points. $\endgroup$
    – Wonder
    Sep 3, 2021 at 13:02
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    $\begingroup$ Is it possible that there is no M point in such an orthorhombic structure, and these papers are incorrect? I know the point (1/2,1/2,0) is the M point in a cubic system, but not sure about orthorhombic... $\endgroup$
    – ProfM
    Sep 3, 2021 at 14:03
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    $\begingroup$ From browsing the paper in the question, I guess there is some attempt at keeping the path uniform over multiple perovskite structures? So points may be labeled without being high-symmetry points? It'd really help if they had drawn the Brillouin zone and path somewhere. $\endgroup$
    – Anyon
    Sep 3, 2021 at 16:37

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