Dear Lorenzo, Thank you for your response! Why should the coordinates of the two Se2 atoms sum to 1 exactly? Does it have to do with the type of unit cell? Is this off of excepted experimental data? What material do you recommend I look at to figure out the errors in my input crystal structure?
Thank you, Varrick Suezaki Department of Physics and Astronomy University of California, Riverside On Tue, Nov 17, 2020 at 7:41 AM Lorenzo Paulatto <[email protected]> wrote: > Your initial structure for the SCF calculation does not look right to me, > one of the Se layers is almost interleaved with a Bi layer. The atomic > positions of the bands calculation is also not perfect: the coordinate of > the two Se2 atoms should sum to 1 exactly, while they do not. This breaks > the crystal symmetry and, for such a small gap as Bi2Se3, is going to have > an impact. > > I have an input file for Bi2Se3, but I think it will save you a lot of > time in the long run, if you work it out on your own once (It surely took > me some time the first time). > > cheers > On 2020-11-17 10:19, Varrick Suezaki wrote: > > Dear PW users, > I'm trying to do a band structure calculation for bi2se3, but the > resulting band structure does not look like other DFT calculations as it is > missing the 0.3eV band gap. I also tried uploading my input file to > SeeK-Path and the crystal structure looked wrong and deformed. Below are > my vc-relax and band input files, is there something I'm missing? I'm using > v6.5 on a CentOS 8 Vmware workstation (Sorry, new to DFT calculations). > > &control > calculation = 'vc-relax' > prefix='bi2se3rel' > restart_mode = 'from_scratch' > outdir= '/home/name/QEoutput' > pseudo_dir='/home/name/quantum_espresso/q-e-qe-6.5/pseudo' > etot_conv_thr = 1e-7 > forc_conv_thr = 1e-6 > / > &system > ibrav = -5, celldm(1) = 18.6947, celldm(4) = 0.9135, nat = 5, ntyp = 3, > ecutwfc = 40, ecutrho = 500, > rhombohedral = .true., > noncolin=.true.,lspinorb=.true.,starting_magnetization=0., > nbnd=78, > vdw_corr = 'grimme-d2' > / > &electrons > conv_thr = 1.0e-9, > / > &ions > / > &cell > cell_dofree='ibrav' > / > ATOMIC_SPECIES > Bi 208.98 Bi.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > Se1 78.96 Se.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > Se2 78.96 Se.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > > ATOMIC_POSITIONS (alat) > Bi 0.3973 0.3973 0.3973 0 0 0 > Bi 0.6027 0.6027 0.6027 0 0 0 > Se1 0.0000 0.0000 0.0000 0 0 0 > Se2 0.2079 0.2079 0.2079 0 0 0 > Se2 0.7821 0.7821 0.7821 0 0 0 > K_POINTS (automatic) > 8 8 8 0 0 0 > > &control > calculation = 'bands' > prefix='bi2se3rel' > restart_mode = 'from_scratch' > wf_collect=.true., > verbosity='high', > outdir= '/home/name/QEoutput' > pseudo_dir='/home/name/quantum_espresso/q-e-qe-6.5/pseudo' > etot_conv_thr = 1e-5 > forc_conv_thr = 1e-4 > / > &system > ibrav = -5, celldm(1) = 18.6947, celldm(4) = 0.9135, nat = 5, ntyp = 3, > ecutwfc = 40, ecutrho = 500, > rhombohedral = .true., > noncolin=.true.,lspinorb=.true.,starting_magnetization=0., > nbnd=78, > vdw_corr = 'grimme-d2' > / > &electrons > conv_thr = 1.0e-8, > diago_full_acc=.true., > / > ATOMIC_SPECIES > Bi 208.98 Bi.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > Se1 78.96 Se.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > Se2 78.96 Se.rel-pbe-dn-rrkjus_psl.1.0.0.UPF > > ATOMIC_POSITIONS crystal > Bi 0.3973 0.3973 0.3973 0 0 0 > Bi 0.6027 0.6027 0.6027 0 0 0 > Se1 1.0000 1.0000 1.0000 0 0 0 > Se2 0.2079 0.2079 0.2079 0 0 0 > Se2 0.7821 0.7821 0.7821 0 0 0 > K_POINTS crystal_b > 5 > 0.00000 0.00000 0.00000 20 !gG > 0.50000 0.50000 0.50000 20 !Z > 0.50000 0.50000 -0.00000 20 !F > 0.00000 0.00000 0.00000 20 !gG > 0.00000 0.00000 -0.50000 20 !L1 > > Thank you, > Varrick Suezaki > Department of Physics and Astronomy > University of California, Riverside > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list > [email protected]https://lists.quantum-espresso.org/mailman/listinfo/users > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
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