Dear Priyank Short answer: use an hybrid functional such as HSE. Bulk Ge is a metal with every flavour of GGA. HTH Giuseppe
On Thursday, February 04, 2016 12:12:32 PM Michael Schofield wrote: > 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 ******************************************************** - Article premier - Les hommes naissent et demeurent libres et égaux en droits. Les distinctions sociales ne peuvent être fondées que sur l'utilité commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la liberté, la propriété, la sûreté et la résistance à l'oppression. ******************************************************** Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00015 - Monterotondo Stazione (RM), Italy Tel + 39 06 90672836 - Fax +39 06 90672316 E-mail: <[email protected]> http://www.ism.cnr.it/english/staff/mattiolig ResearcherID: F-6308-2012 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
