thank you Dario. When I use VASP I get the exact same result as mentioned in the reference you have atatched but with quantum espresso I get significantly different result especially the band gap. If you can have a look at the relax input file I have attached in the email and let met know if I should add anything else ?
&CONTROL calculation='vc-relax', outdir='./', prefix='calc', pseudo_dir='./', verbosity='high', / &SYSTEM ibrav=0, celldm(1)= 8.276999830d0 nat=4, ntyp=1, ecutwfc=60, ecutrho=360, input_dft='lda', occupations='smearing', smearing='mv', degauss=0.005d0, / &ELECTRONS conv_thr=1d-06, mixing_beta=0.7d0, / &IONS ion_dynamics='bfgs' / &CELL cell_dynamics='bfgs' cell_dofree='2Dshape' / ATOMIC_SPECIES P 30.973800d0 P.pw-mt_fhi.UPF ATOMIC_POSITIONS {crystal} P 0.090000004 0.000000000 0.050195117 P 0.909999967 0.000000000 0.949804902 P 0.590000033 0.500000000 0.949804902 P 0.409999996 0.500000000 0.050195117 K_POINTS {automatic} 12 12 1 0 0 0 CELL_PARAMETERS {alat} 1.0000000000000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 0.7511415530000000 0.0000000000000000 0.0000000000000000 0.0000000000000000 4.68036529200000000 thank you Gautam GAUTAM GADDEMANE DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING UNIVERSITY OF TEXAS AT DALLAS On Thu, Oct 5, 2017 at 3:54 PM, dario rocca <roc...@gmail.com> wrote: > Dear Gautam, > The values you get are not completely impossible. > Try with PBE, since there are for sure a couple of calculations in the > literature to compare with. > For example > https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.085402 > Best, > Dario > > On Thu, Oct 5, 2017 at 10:31 PM, Gautam Gaddemane <gautam...@gmail.com> > wrote: > >> 4.45 A and 3.26 A and a band gap of 0.67eV. >> >> GAUTAM GADDEMANE >> DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING >> UNIVERSITY OF TEXAS AT DALLAS >> >> On Thu, Oct 5, 2017 at 3:28 PM, Matthieu Fortin-Deschênes < >> matthieu.fortin-desche...@polymtl.ca> wrote: >> >>> What values of lattice parameters and band gap did you get? With LDA >>> you expect some differences compared to experimental values. >>> >>> Matthieu >>> >>> Gautam Gaddemane <gautam...@gmail.com> a écrit : >>> >>> > Dear All, >>> > >>> > I am trying to calculate the bands tructure for monolayer phosphorene >>> and I >>> > am just a week old in using quantum espresso. >>> >> From the bulk unit cell I prepared an input file to relax the >>> structure but >>> > I was not able to get a good lattice constant nor a good band gap. It >>> would >>> > be very helpful if someone would guide me in this procedure. >>> > I have attahced the file I used to relax in this email >>> > >>> > >>> > &CONTROL >>> > calculation='vc-relax', >>> > outdir='./', >>> > prefix='calc', >>> > pseudo_dir='./', >>> > verbosity='high', >>> > / >>> > >>> > &SYSTEM >>> > ibrav=0, >>> > celldm(1)= 8.276999830d0 >>> > nat=4, >>> > ntyp=1, >>> > ecutwfc=60, >>> > ecutrho=360, >>> > input_dft='lda', >>> > occupations='smearing', >>> > smearing='mv', >>> > degauss=0.005d0, >>> > / >>> > >>> > &ELECTRONS >>> > conv_thr=1d-06, >>> > mixing_beta=0.7d0, >>> > / >>> > &IONS >>> > ion_dynamics='bfgs' >>> > / >>> > >>> > &CELL >>> > cell_dynamics='bfgs' >>> > cell_dofree='2Dshape' >>> > / >>> > ATOMIC_SPECIES >>> > P 30.973800d0 P.pw-mt_fhi.UPF >>> > >>> > ATOMIC_POSITIONS {crystal} >>> > >>> > P 0.090000004 0.000000000 0.050195117 >>> > P 0.909999967 0.000000000 0.949804902 >>> > P 0.590000033 0.500000000 0.949804902 >>> > P 0.409999996 0.500000000 0.050195117 >>> > >>> > K_POINTS {automatic} >>> > >>> > 12 12 1 0 0 0 >>> > >>> > CELL_PARAMETERS {alat} >>> > >>> > 1.0000000000000000 0.0000000000000000 0.0000000000000000 >>> > 0.0000000000000000 0.7511415530000000 0.0000000000000000 >>> > 0.0000000000000000 0.0000000000000000 4.68036529200000000 >>> > >>> > >>> > thank you >>> > Gautam >>> > >>> > GAUTAM GADDEMANE >>> > DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING >>> > UNIVERSITY OF TEXAS AT DALLAS >>> >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum@pwscf.org >>> http://pwscf.org/mailman/listinfo/pw_forum >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum@pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > _______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum >
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