[Pw_forum] Relax Calculation in ZnO

[Duy Le]

Hi Angga,

1. tetrahedra is not a suitable method for force/relaxation...
calculations.
There is no fundamental problem of using smearing for
semi-conductor/insulator. The only problem is it takes a little bit more
time to converge.

2. No. Unless you need some quantities or files that were not calculated or
generated during relaxation.
 ----------------------------------------------------
Duy Le
Postdoctoral Associate
Department of Physics
University of Central Florida.
Website: http://www.physics.ucf.edu/~dle


On Thu, Jan 10, 2013 at 3:12 AM, Angga Fauzi <angga_dito_fauzi at yahoo.com>wrote:

> Dear all QE users,
>
> I am trying to run relax calculation for my ZnO system. There are
> something I want to ask.
>
>    1. In running relax calculation, what occupations should I use? I am
>    trying to use occupations = 'tetrahedra', but it doesn't work. I am afraid
>    if I use occupations = 'smearing', my result calculation doesn't valid
>    since ZnO is a semiconductor, not a metal.
>    2. After my relax calculation is done, should I run a scf calculation
>    again with atomic positions I get from relax calculation?
>
> My input file is below.
>
>  &CONTROL
>                        title = 'ZnO' ,
>                  calculation = 'relax',
>                       outdir = '$TMP_DIR' ,
>                   pseudo_dir = '$PSEUDO_DIR' ,
>                       prefix = 'ZnO',
>                   wf_collect = .true.
>                      tprnfor = .true.
>                forc_conv_thr = 1.0d-3
>  /
>  &SYSTEM
>                        ibrav = 4,
>                    celldm(1) = 12.998 ,
>                    celldm(3) = 1.625 ,
>                          nat = 32,
>                         ntyp = 2,
>                      ecutwfc = 30.0,
>                  occupations = 'smearing',
>                     smearing = 'mv',
>                      degauss = 0.02,
>                        nspin = 2,
>    starting_magnetization(1) = 0.0,
>  /
>  &ELECTRONS
>                  mixing_beta = 0.62
>                     conv_thr = 1.0d-3
>  /
>  &IONS
>                 ion_dynamics = 'bfgs',
>                ion_positions = 'default',
>                  phase_space = 'full',
>            pot_extrapolation = 'atomic',
>            wfc_extrapolation = 'none',
>             remove_rigid_rot = .false.
>  /
> ATOMIC_SPECIES
>    Zn   65.38000  Zn.pbe-van.UPF
>     O   15.99900  O.pbe-van_ak.UPF
> ATOMIC_POSITIONS crystal
>    Zn      0.166666600    0.333333300    0.000000000
>     O      0.166666600    0.333333300    0.189600000
>    Zn      0.333333300    0.166666600    0.250000000
>     O      0.333333300    0.166666600    0.439600000
>    Zn      0.666666600    0.333333300    0.000000000
>     O      0.666666600    0.333333300    0.189600000
>    Zn      0.833333300    0.166666600    0.250000000
>     O      0.833333300    0.166666600    0.439600000
>    Zn      0.166666600    0.833333300    0.000000000
>     O      0.166666600    0.833333300    0.189600000
>    Zn      0.333333300    0.666666600    0.250000000
>     O      0.333333300    0.666666600    0.439600000
>    Zn      0.666666600    0.833333300    0.000000000
>     O      0.666666600    0.833333300    0.189600000
>    Zn      0.833333300    0.666666600    0.250000000
>     O      0.833333300    0.666666600    0.439600000
>    Zn      0.166666600    0.333333300    0.500000000
>     O      0.166666600    0.333333300    0.689600000
>    Zn      0.333333300    0.166666600    0.750000000
>     O      0.333333300    0.166666600    0.939600000
>    Zn      0.666666600    0.333333300    0.500000000
>     O      0.666666600    0.333333300    0.689600000
>    Zn      0.833333300    0.166666600    0.750000000
>     O      0.833333300    0.166666600    0.939600000
>    Zn      0.166666600    0.833333300    0.500000000
>     O      0.166666600    0.833333300    0.689600000
>    Zn      0.333333300    0.666666600    0.750000000
>     O      0.333333300    0.666666600    0.939600000
>    Zn      0.666666600    0.833333300    0.500000000
>     O      0.666666600    0.833333300    0.689600000
>    Zn      0.833333300    0.666666600    0.750000000
>     O      0.833333300    0.666666600    0.939600000
> K_POINTS automatic
>   12 12 8   0 0 0
>
> Thank you very much for your attention.
>
> Regards,
> Angga
>
> Angga Dito Fauzi
> Undergraduate Student
> Department of Physics, Faculty of Mathematics and Natural Sciences
> Universitas Indonesia, Depok 16424, Indonesia
> Phone: +628124139348
> Email: angga_dito_fauzi at yahoo.com
>
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