Hi all, I'm doing Berry Phase calculations for the first time for BiFeO3. I met with some problems in setting nbnd values for the scf and nscf calculations. And I can't find an answer in previous forum post.
I used the pseudopotentials available in the website http://www.pwscf.org/pseudo.php They are: Bi.pbe-d-mt.UPF Fe.pbe-nd-rrkjus.UPF O.pbe-mt.UPF and from the pseudopotentials, there should be 41 electrons in a cell. From the manual nbnd = nelect/2. I've tried different combinations of nbnd values for scf and nscf jobs and non was able to give me the polarization value. The following are the some selected cases and their error msg: Case(1) *.scf, nbnd=21; *.nscf, nbnd=21 Both jobs crash Error for scf: too few bands Error for nscf: starting and expected charges differ Case(2) *.scf, nbnd=43; *.nscf, nbnd=42 Scf converged. Nscf crashed. Error for nscf: Polarization only for insulators and no empty bands Case(3) *.scf, nbnd=42; *.nscf, nbnd=42 Scf converged. Nscf crashed. Error for scf: too few spin up bands Error for nscf: starting and expected charges differ My input files are as follows: SCF JOB: &control calculation = 'scf', restart_mode = 'from_scratch' pseudo_dir = '/Home6/cc/ihpclimc/BP_CAL/PPOT' outdir = '/Scratch/ihpclimc/BERRY_PHASE_CALCULATIONS/Try_BP/OUTDIR', / &system ibrav=5 celldm(1)=10.6523, celldm(4)=0.50988, nat=10 ntyp=3 nbnd=42 ecutwfc=50.0 occupations = 'fixed' degauss=0.00 nspin=2 multiplicity=5 lda_plus_u=.true. Hubbard_U(2)=6 / &electrons conv_thr = 1e-12, mixing_beta=0.3, diagonalization='cg', / ATOMIC_SPECIES Bi 209.0 Bi.pbe-d-mt.UPF Fe 55.85 Fe.pbe-nd-rrkjus.UPF O 16.00 O.pbe-mt.UPF ATOMIC_POSITIONS crystal Bi 0.000 0.000 0.000 0 0 0 Bi 0.500 0.500 0.500 0 0 0 Fe 0.219 0.219 0.219 Fe 0.719 0.719 0.719 O 0.445 0.032 0.897 O 0.897 0.445 0.032 O 0.032 0.897 0.445 O 1.397 0.532 0.945 O 0.532 0.945 1.397 O 0.945 1.397 0.532 K_POINTS {automatic} 1 1 1 1 1 1 NSCF JOB: &control calculation = 'nscf', pseudo_dir = '/Home6/cc/ihpclimc/BP_CAL/PPOT' outdir = '/Scratch/ihpclimc/BERRY_PHASE_CALCULATIONS/Try_BP/OUTDIR', lberry = .true. gdir = 3 nppstr = 7 / &system ibrav=5 celldm(1)=10.6523, celldm(4)=0.50988, nat=10 ntyp=3 nbnd=42 ecutwfc=50.0 occupations = 'fixed' degauss=0.00 nspin=2 multiplicity=5 lda_plus_u=.true. Hubbard_U(2)=6 / &electrons conv_thr = 1e-12, mixing_beta=0.3, diagonalization='cg', / ATOMIC_SPECIES Bi 209.0 Bi.pbe-d-mt.UPF Fe 55.85 Fe.pbe-nd-rrkjus.UPF O 16.00 O.pbe-mt.UPF ATOMIC_POSITIONS crystal Bi 0.000 0.000 0.000 0 0 0 Bi 0.500 0.500 0.500 0 0 0 Fe 0.219 0.219 0.219 Fe 0.719 0.719 0.719 O 0.445 0.032 0.897 O 0.897 0.445 0.032 O 0.032 0.897 0.445 O 1.397 0.532 0.945 O 0.532 0.945 1.397 O 0.945 1.397 0.532 K_POINTS {automatic} 4 4 4 1 1 1 Can anyone help? Thanks, Rgds Freda Lim Institute of High Performance Computing 1 Fusionopolis Way, #16-16 Connexis Singapore 138632 Email: limch at ihpc.a-star.edu.sg<mailto:limch at ihpc.a-star.edu.sg> ________________________________ This email is confidential and may be privileged. If you are not the intended recipient, please delete it and notify us immediately. Please do not copy or use it for any purpose, or disclose its contents to any other person. Thank you. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100630/ef30e50e/attachment-0001.htm
