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Hi All,

I am trying to calculate the band gap of NiO by the modified Becke-Johnson meta-GGA. Below is my input. The output band gap is only ~ 2eV, half of the reported value of ~4 eV by the PRL paper of Tran & Blaha.

I there anything wrong in my input?

Thanks for reading.

Linhui

#===========================================
# NiO modified Becke-Johnson metaGGA band structure

ndtset 3

# === cell
acell 3*7.92
rprim 0.0 1/2 1/2
1/2 0.0 1/2
1.0 1.0 0.0

# === atom
natom 4
ntypat 2
znucl 28.0 8.0
typat 1 1 2 2
xred 0 0 0
0.0 0.0 0.5
0.5 0.5 0.25
0.5 0.5 0.75

# === spin
nsppol 1
nspden 2
nspinor 1
spinat 0 0 1 0 0 -1 0 0 0 0 0 0

# === k point
ngkpt 8 8 4
chksymbreak 0

# === wavefunction calculation
ecut 80
nstep 900
tolwfr 1.0d-8
nband 30

#Second dataset, mGGA calculation, scf
getwfk2 -1
ixc2 -12208
usekden2 1
prtkden2 1

#Third dataset, non-SCF mGGA calculation
iscf3 -2
ixc3 -12208
getden3 -1
usekden3 1
kptopt3 -3
nband3 70
ndivk3 50 50 50

kptbounds3 0.0 0.0 0.0
0.5 0.0 0.0
0.0 0.5 0.5
1.0 1.0 1.0