I want to learn how to solve Harper's equation and plot the Hofstader butterfly spectrum numerically. Can anyone suggest references/links where this is done?
2 Answers
Have a look at a recent paper [1]. This may be what you are looking for. Since it is recent, you can look at its references to look backwards for more traditional methods that are perhaps less accurate.
[1] Colbrook, Matthew J., Bogdan Roman, and Anders C. Hansen. "How to compute spectra with error control." Physical review letters 122.25 (2019): 250201.
The documentation of the open-source Python package HofstadterTools (https://hofstadter.tools) gives a thorough introduction to the numerical solution of Harper's equation. This software analyzes the energy spectrum of a generalized Hofstadter model on any regular Euclidean lattice, and can be applied to compute key properties of the band structure, such as quantum geometry and topology, as well as plot colored Hofstadter butterflies and Wannier diagrams.