Hi all, I am currently simulating band diagram for Phosphorus doped Silicon. I am using 53 Si atoms and 1 P atom for computation. When I computed the band diagram, it resulted in direct band gap, which is not true case for Silicon. I have not relaxed the system.
My input file is as follows, &control calculation = 'scf', restart_mode='from_scratch', verbosity = 'high', prefix = 'Silicon_P_54_relax', tstress = .true., tprnfor = .true., pseudo_dir = '.', outdir = 'out_P_rel', wf_collect=.true., max_seconds=10800, / &system ibrav=2, celldm(1) = 30.787040, nat=54, ntyp=2, ecutwfc=50, ecutrho=400.0d0, input_dft='PBE', nbnd=120, occupations='smearing', degauss=0.05, / &electrons diagonalization='david', mixing_mode = 'plain', mixing_beta = 0.7, conv_thr = 1.0d-6, / ATOMIC_SPECIES Si 28.085500 Si.pbe-n-rrkjus_psl.0.1.UPF P 30.973800 P.pbe-n-rrkjus_psl.0.1.UPF ATOMIC_POSITIONS (alat) Si 0.000000 0.000000 0.000000 .................................. P 0.083333 0.083333 0.083333 ............................. Si 0.750000 0.750000 0.750000 K_POINTS (automatic) 5 5 5 0 0 0 Could anyone please explain the reason behind this change from indirect to direct bandgap? Or any suggestion to solve this problem? Thank you very much. Best, -- Mohammad Abu Raihan Miah PhD Student Department of Electrical and Computer Engineering (ECE) <http://www.ece.ucsd.edu/> University of California, San Diego <http://www.ucsd.edu/>
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