for non spin polarization
if
nelect=8
nbands=8
nkpts=1
say we want to occupy the first 3 bands, leaving the following 2 half occupied and the remaining empty
FERWE = 3*1 2*0.5 3*0
for spin polarization
FERWE = 5*1 3*0 (spin up)
FERDO = 3*1 5*0 (spin down)
In the case where there is more than one irreducible kpoint
for instance NKPTS = 3
no spin
FERWE = 3*1 2*0.5 3*0 3*1 2*0.5 3*0 3*1 2*0.5 3*0 i.e. repeats the definition of occupation you want for each k-point
spin
FERWE = 5*1 3*0 5*1 3*0 5*1 3*0 (spin up)
FERDO = 3*1 5*0 3*1 5*0 3*1 5*0 (spin down)
参考：
question about FERWE and FERDO
Easy manual occupancy of Kohn-Sham levels with FERWE and FERDO