This is a collection of input and output files that were used to produce all the data reported in the following publication: Tommaso Gorni, Oscar Baseggio, Pietro Delugas, Iurii Timrov, and Stefano Baroni, "First-principles study of 1 the gap in the spin excitation spectrum of the CrI3 honeycomb ferromagnet", accepted to Phys. Rev. B Letter, arXiv:2212.09516 Calculations were performed using the open-source Quantum ESPRESSO distribution which can be downloaded from www.quantum-espresso.org. The following codes of Quantum ESPRESSO were used: pw.x - the code that performs ground-state DFT calculations turbo_magnon.x - the code to compute magnons using TDDFPT turbo_spectrum.x - the post-processing program to plot the magnetic spectra DESCRIPTION OF FOLDERS: - DFT: input and ouput files for the DFT ground-state calculation - TDDFT: input and ouput files for the TDDFT calculations of magnons - Fitting_k_cones: scripts to perform the fitting of cones around the K point