Hi, Several comments: 1, it seems you use NCPP pseudopotentials . Therefore , 40 Ry for enenrgy cutoff is not enough to get convergent results. 2, You can do alignment of so-called fermi level, which is meaningless since you deal with a semiconductor. 3, Underestimation of energy gap is well accepted in LDA calculations.
Hope helps Regards On Fri, Aug 28, 2009 at 3:37 AM, nand <rana_nand at yahoo.com> wrote: > > > Sir, > I am a research scholar at the Ranchi university, India. It will be a great > help if you can help me with the band structure calculation for GaAs using > Quantum Espresso. > I do not get the correct band structure even with the input file you > mentioned below. I am attaching the band structure pdf file which I produced > using input file given below. As you can see that the fermi level is > wrongly located and the band gap is badly underestimated. Please tell me > about the possible fault(s) possible in my calculation. > Thanking you in advance. > Nand Rana, > (Research Scholar) > Ranchi, India. > > ----------------------------------- > input file for the scf calculation: > > &control > calculation='scf', > outdir='./tmp', > prefix='gaas', > pseudo_dir='/espresso-4.0.4/pseudo' > / > > &system > ibrav=2, > celldm(1)=10.6827, > nbnd=8, > nat=2, > ntyp=2, > ecutwfc=40.0d0, > occupations='fixed', > nspin=1 > / > > &electrons > conv_thr=1d-6, > mixing_beta=0.7, > diagonalization='david' > / > > ATOMIC_SPECIES > Ga 69.723 Ga.pz-bhs.UPF > As 74.92160 As.pz-bhs.UPF > > ATOMIC_POSITIONS alat > Ga 0.0 0.0 0.0 > As 0.25 0.25 0.25 > > K_POINTS automatic > 10 10 10 0 0 0 > > > > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hai-Ping Lan Department of Electronics , Peking University , Bejing, 100871 lanhaiping at gmail.com, hplan at pku.edu.cn -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090828/d3318080/attachment.htm
