How to install “GroupTheory” package in Mathematica? I am using Mathematica v12.0, and I try to install “GroupTheory” via “Palettes –> Install Palette …”. But it does not work. Thank you very much.

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Qilin GUO Selected answer as best 22. December 2020
Qilin GUO

Now I find the correct way to install GTpack, see “Appendix D: Technical Remarks on GTPack” of the book “Group Theory in Solid State Physics and Photonics: Problem Solving with Mathematica” by Wolfram Hergert and R. Matthias Geilhufe.
If one want to remove a undesirable palettes, just run the following command in Mathematica to open the path of the palettes:
FileNameJoin[{$UserBaseDirectory, “SystemFiles”, “FrontEnd”,