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i have used also 500 bands. occopt 7, occopt 3, again default settings(75 bands). That is, i have tried everything. But bandgap didn't change. Band gap is between 78 and 79. But it must be between 72 and 73. Help pls?

All (fhi, tm,...) LDA and GGA pseudopotentials and paw data sets have been tried but results were same. Why?


My imput file:

#-----------------------------------------------------------

#optcell


toldfe 1.0d-6
iscf 7
nband 138
#-----------------------------------------------------------


# Data common to the three different datasets

# Definition of the unit cell:
acell 5.39840 8.30183 4.46013 Angstrom
angdeg 90 90 90
nstep 100
prtcif 1
ecut 74
npulayit 16
nline 12
optforces 1
prtden 1

# Definition of the atoms
znucl 28 8 5
ntypat 3
natom 22
typat 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3
xred
0.000000 0.000000 0.000000
0.500000 0.500000 0.500000
0.000000 0.316280 0.500000
0.000000 0.683720 0.500000
0.500000 0.183720 0.000000
0.500000 0.816280 0.000000
0.676100 0.000000 0.247600
0.323900 0.000000 0.752400
0.176100 0.500000 0.252400
0.823900 0.500000 0.747600
0.796900 0.139600 0.698100
0.203100 0.860400 0.301900
0.203100 0.139600 0.301900
0.796900 0.860400 0.698100
0.296900 0.360400 0.801900
0.703100 0.639600 0.198100
0.703100 0.360400 0.198100
0.296900 0.639600 0.801900
0.747500 0.000000 0.541000
0.252500 0.000000 0.459000
0.247500 0.500000 0.959000
0.752500 0.500000 0.041000


# Definition of the k-point grid
kptopt 1
ngkpt 4 4 4
nshiftk 1
shiftk 0.0 0.0 0.0

#-----------------------------------------------------------

Help pls...