[QE-developers] “Ghost” SCF calculation for finer FFT grid

[Jacob Williams]

Dear all,


I am working on the self-interaction correction method of https://doi.org/10.1021/acs.jpclett.9b03888, applied to extended systems. I need to calculate Coulomb repulsion integrals between Wannier densities, which have the periodicity of the unfolded Born-von Karman supercell. I’d like to do it in reciprocal space, for which I need to perform an FFT using the unfolded supercell. However, I can use the output from the (k-sampled) normal unit cell, so I would like to obtain the FFT of the Wannier function densities on the larger cell without having to re-run a larger/unfolded SCF calculation, which gets expensive.

Is there a ready way to initialize the FFT machinery without redoing the entire SCF calculation? If not I thought it might be possible to set up an empty or “ghost” pw.x input file to initialize the unfolded cell FFT machinery and read in the k-sampled pw.x output from disk.

Thank you for your help!

Sincerely yours,

Jacob Williams
PhD Student, Yang group
Duke University Dept. of Chemistry
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