[Pw_forum] TiO2 001 Slab Convergence

[Jia Chen]

Dear Will,

Can you elaborate on what do you mean by it never reaches the minimum? It
is hard for me to see what actually went wrong.

On Sun, Apr 23, 2017 at 9:15 PM, William Joseph Ivan DeBenedetti <
wjd74 at cornell.edu> wrote:

> Dear QE Users,
>
> I am attempting to perform convergence tests on an 001 slab of TiO2
> (anatase) (1x1 with 1 layer of TiO2 in the c direction). While I am not
> getting any errors when attempting a ‘relax’ calculation, I am finding the
> the slab never really reaches a global minimum. I have decreased my
> convergence threshold and implemented Gaussian smearing but am still not
> reaching convergence. I have a ~ 15 angstrom vacuum layer implemented in
> the CELL_PARAMETERS block. Can someone who has more experience with surface
> slabs assist? This will eventually be used with an adsorbate for further
> studies.
>
> I am including my input file:
>
> &CONTROL
>  calculation = 'relax',
>  restart_mode = 'from_scratch',
>  prefix='ANA',
>  pseudo_dir='/work/04703/wjid/Pseudo',
>  tstress=.true.,
>  tprnfor=.true.,
> /
> &SYSTEM
>  ibrav=0,
>  nat=12,
>  ntyp=2,
>  ecutwfc=60,
>  ecutrho=500,
>  occupations='smearing',
>  smearing='gaussian',
>  degauss=0.01
> /
> &ELECTRONS
>  conv_thr = 1.0D-6,
>  mixing_mode = 'local-TF',
>  mixing_beta = 0.3d0,
>  diagonalization = 'cg',
> /
> &IONS
>  ion_dynamics='bfgs',
> /
> &CELL
>  cell_dynamics = 'bfgs',
>  press=0.1d0,
> /
> ATOMIC_SPECIES
>  Ti 47.88d0 Ti_PBE.UPF
>  O  16.00d0 O_PBE.UPF
>
> CELL_PARAMETERS
> 7.18366994d0   0.0d0      0.0d0
> 0.0d0   7.18366994d0      0.0d0
> 0.0d0   0.0d0     41.94037d0
>
> ATOMIC_POSITIONS crystal
> Ti     0.40773000000000      0.40773000000000   0.14705900000000
> Ti     0.59227000000000      0.59227000000000   0.61764700000000
> Ti     0.40773000000000      0.59227000000000   0.38235300000000
> Ti     0.59227000000000      0.40773000000000   0.85294100000000
> O      0.40773000000000      0.40773000000000   0.33529400000000
> O      0.59227000000000      0.59227000000000   0.80588200000000
> O      0.40773000000000      0.59227000000000   0.57058800000000
> O      0.59227000000000      0.40773000000000   0.10000000000000
> O      0.59227000000000      0.40773000000000   0.66470600000000
> O      0.40773000000000      0.59227000000000   0.19411800000000
> O      0.59227000000000      0.59227000000000   0.42941200000000
> O      0.40773000000000      0.40773000000000   0.90000000000000
>
> K_POINTS automatic
>   4 4 1 0 0 0
>
>
>
>
> Thanks,
>
> Will DeBenedetti
> Doctoral Candidate
> Cornell University
>
>
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