The Fermi surface is visualized by XCrySDen  and FermiSurfer [143,144]. When you perform calculations of the density of states by the following keywords:
Dos.fileout on # on|off, default=off Dos.Erange -20.0 20.0 # default = -20 20 Dos.Kgrid 61 61 61 # default = Kgrid1 Kgrid2 Kgrid3 FermiSurfer.fileout on # default = off, on/offyou will obtain a file 'System.Name.FermiSurf0.bxsf' which is readable by XCrySDen  and a file 'System.Name.FermiSurf_s0_aA.frmsf' which is readable by FermiSurfer [143,144], where 'System.Name' is 'System.Name', and A is the serial number of atoms. To obtain the files readable by FermiSurfer, you need to switch on the keyword 'FermiSurfer.fileout'. As well as 'Dos.Fileout', 'DosGauss.fileout' can also be used for the purpose, while the files readable by FermiSurfer are not generated in the case of 'DosGauss.fileout'. In case of spin-polarized calculations, for XCrySDen two files 'System.Name.FermiSurf0.bxsf' and 'System.Name.FermiSurf1.bxsf' are generated for spin-up and spin-down states, respectively, and for FermiSurfer two files 'System.Name.FermiSurf_s0_aA.frmsf' and 'System.Name.FermiSurf_s1_aA.frmsf' are generated for spin-up and spin-down states, respectively. The data file for FermiSurfer can be used to display the color plot of the contribution from each atoms.