Dear sir/madam, I am trying to calculate the bulk band structure for Germanium using GGA exchange-correlation with PAW basis, but the band gap is coming out to be almost zero. I know DFT underestimates the band gap but it is coming almost zero (~0.03eV). Is there any means by which I can get more accurate band gap.
My input script is here: &control calculation = 'nscf', verbosity = 'high', restart_mode = 'from_scratch', prefix = 'Ge_bulk_nscf', tstress = .false., tprnfor = .false., pseudo_dir = '/home/Software/QE/pseudopotentials/upf_files/', outdir = './output/' / &system ibrav=2, celldm(1) = 10.690937, nat=2, ntyp=1, nbnd = 12, ecutwfc=60, ecutrho= 600, / &electrons diagonalization='david', mixing_mode = 'plain', mixing_beta = 0.7, conv_thr = 1.0d-6, electron_maxstep = 500, / ATOMIC_SPECIES Ge 72.640000 Ge.pbe-kjpaw.UPF ATOMIC_POSITIONS crystal Ge 0.000000 0.000000 0.000000 Ge 0.250000 0.250000 0.250000 K_POINTS crystal_b 6 0.0 0.0 0.0 100 0.0 0.5 0.0 100 0.0 0.375 -0.375 100 -0.25 0.25 -0.5 100 -0.5 0.0 -0.5 100 0.0 0.0 0.0 1 ----------------------------------------------------------------- PFA the band structure I am getting from it. Any help/suggestions will be helpful. Thanks Priyank Dept. of EE IIT Kanpur, India
Ge_bulk_GGA_BS.pdf
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