EPW Forum

Dear all

I plot the XX.fs.frmsf and XX.imag_aniso_gap0_005.00.frmsf files using the Fermisurfer program. They are different in bands. Does the XX.imag_aniso_gap0_005.00.frmsf file plot some gaps not on the Fermi surface or these gaps are not convergent? I think the Fermi surface shoud be same plot by these two files. Fig. 1 is ploted by XX.fs.frmsf, Fig. 2 is ploted by XX.imag_aniso_gap0_005.00.frmsf.

Dear Xiaming,

There's a knack for correctly outputting a frmsf file from the superconducting module.
The previous versions (<= v.5.7) replace eigenvalues outside the fsthick window by a dummy value. That's why you sometimes get fake Fermi surfaces. To avoid this problem, you may increase the fsthick value so that the bands crossing the Fermi energy do not have a dummy value.
We have modified the module to output correct eigenvalues into a frmsf file in the latest version even if fsthick is small. Please try the latest version to get correct Fermi surfaces.

Even in the latest version, the gap functions outside the fsthick window are not calculated and are replaced by 0. Therefore, the interpolation performed in Fermisurfer may not work well where values are replaced by 0, and a dot-like pattern may appear on the Fermi surface. If you take a large enough fsthick value, interpolation will work well. Alternatively, increasing the size of the k grid might improve the visualization.

Best,
Hitoshi