Why the lines in the band structure appear jagged?

[Samira]

Dear all, I calculated the Band Gap of SrTiO3 with ABINIT, BUT it appear jagged not curve and smoth. Could you please let me know wht this is happining ? The following is my input files :
acell 3.9244716293 3.9244716293 3.9244716293 Angstr
angdeg 90 90 90
nband 30
ecut 34
#chksymtnons=0
nstep 500
toldfe 1.0d-8
ngkpt 12 12 12

prtwf 1
#pawecutdg 60

znucl 8 22 38
ntypat 3
tsmear 0.01
typat 3 2 3*1
natom 5
xred
0.000000000 0.000000000 0.000000000
0.500000000 0.500000000 0.500000000
0.000000000 0.500000000 0.500000000
0.500000000 0.000000000 0.500000000
0.500000000 0.500000000 0.000000000
#############################################3
#Dataset 2 N-SCF calculation
iscf?2 -2
getden?2 -1
kptopt?2 -3
ndivsm?2 20
tolwfr?2 1.0d-12
kptbounds?2
0.0 0.0 0.0 # Gamma
0.5 0.5 0.0 # M
0.5 0.0 0.0 # X
0.0 0.0 0.0 # Gamma
0.5 0.5 0.5 # R
diemac 12.0

[gonze]

Dear Samira, It seems that you are visualizing the eigenenergies of the first dataset, not the one of the second dataset. So, you see the 12x12x12 k point grid energies, not the band structure along the Gamma-M-X-Gamma-R lines that corresponds to dataset 2. Best, Xavier.