[QE-users] Dipole correction: electrostatic potential partially corrected

[Stefano de Gironcoli]

I think the code does what you ask for

it set the dipole double layer stating al 95% (emaxpos = 0.95) of you 
cell extending for 5% up to 100% (eopreg = 0.05 )

the slope from 95% to 100$% is just the internal potential drop in the 
double layer...

stefano

On 01/05/20 16:57, Pacome NGUIMEYA wrote:
> Dear QE users,
>
> I generated a (1x1) surface slab ( with 20-angstroms vacuum) of the 
> (001) surface using a 5-layer slab model.
> I included the dipole correction to cancel the artificial field as my 
> slab is asymmetric.
>
> As you can see in the picture here attached, the correction did not 
> work on both sides. In fact, I got a perfectly
> flat potential in the vacuum region to the left of the slab but not to 
> the right.
>
> I tried different values for emaxpos and eopreg following the example 
> on this blog 
> https://christoph-wolf.at/2018/05/02/dipole-correction-in-quantum-espresso/, 
> but only those in the input file below could give something close to 
> the expected result.
>
> PS: My slab is centered at the center of the cell.
>
> Can you please advise how I can get this fixed?
>
> Thanks in advance for your help
>
> &CONTROL
>                  calculation = 'scf',
>                       prefix = 'TaAs',
>                 restart_mode = 'from_scratch',
>                   pseudo_dir = './',
>                       outdir = './',
>                etot_conv_thr = 1.0e-5,
>                   wf_collect = .true.,
>                    verbosity = 'high',
>                      tefield = .true.,
>                     dipfield = .true.
> /
> &SYSTEM
>                        ibrav = 0,
>                          nat = 40,
>                         ntyp = 2,
>                      ecutwfc = 60,
>                      ecutrho = 480,
>                  occupations = 'smearing',
>                     smearing = 'm-p',
>                      degauss = 0.03,
>                         eamp = 0,
>                         edir = 3,
>                      emaxpos = 0.95,
>                       eopreg = 0.05
> /
> &ELECTRONS
>              diagonalization = 'david',
>                  mixing_mode = 'local-TF',
>                  mixing_beta = 0.7,
>                     conv_thr = 1.0e-6,
>             electron_maxstep = 300
> /
> ATOMIC_SPECIES
>  Ta  180.9480000000    Ta.pbe-spn-kjpaw_psl.1.0.0.UPF
>  As   74.9216000000    As.pbe-n-kjpaw_psl.1.0.0.UPF
> CELL_PARAMETERS {angstrom}
>  3.469828240000000       0.000000000000000 0.000000000000000
>  0.000000000000000       3.469828240000000 0.000000000000000
>  0.000000000000000       0.000000000000000  76.718787642331264
> ATOMIC_POSITIONS {angstrom}
>   As  0.0000000000000000  1.7349141199999991  63.3017546359999841
>   As  0.0000000000000000  1.7349141199999991  51.5641730759999888
>   As  0.0000000000000000  1.7349141199999991  39.8265915159999935
>   As  0.0000000000000000  1.7349141199999991  28.0890099560000053
>   As  0.0000000000000000  1.7349141199999991  16.3514283959999887
>   As  0.0000000000000000  0.0000000000000000  66.2361500259999900
>   As  0.0000000000000000  0.0000000000000000  54.4985684659999947
>   As  0.0000000000000000  0.0000000000000000  42.7609869059999994
>   As  0.0000000000000000  0.0000000000000000  31.0234053459999899
>   As  0.0000000000000000  0.0000000000000000  19.2858237859999946
>   As  1.7349141199999991  0.0000000000000000  57.4329638559999935
>   As  1.7349141199999991  0.0000000000000000  45.6953822959999911
>   As  1.7349141199999991  0.0000000000000000  33.9578007359999958
>   As  1.7349141199999991  0.0000000000000000  22.2202191759999934
>   As  1.7349141199999991  0.0000000000000000  10.4826376159999981
>   As  1.7349141199999991  1.7349141199999991  60.3673592459999924
>   As  1.7349141199999991  1.7349141199999991  48.6297776859999971
>   As  1.7349141199999991  1.7349141199999991  36.8921961259999875
>   As  1.7349141199999991  1.7349141199999991  25.1546145659999922
>   As  1.7349141199999991  1.7349141199999991  13.4170330059999898
>   Ta  1.7349141199999991  0.0000000000000000  62.3364794036686973
>   Ta  1.7349141199999991  0.0000000000000000  50.5988978436687091
>   Ta  1.7349141199999991  0.0000000000000000  38.8613162836686996
>   Ta  1.7349141199999991  0.0000000000000000  27.1237347236686972
>   Ta  1.7349141199999991  0.0000000000000000  15.3861531636687161
>   Ta  1.7349141199999991  1.7349141199999991  65.2708747936686962
>   Ta  1.7349141199999991  1.7349141199999991  53.5332932336687009
>   Ta  1.7349141199999991  1.7349141199999991  41.7957116736687126
>   Ta  1.7349141199999991  1.7349141199999991  30.0581301136687102
>   Ta  1.7349141199999991  1.7349141199999991  18.3205485536687149
>   Ta  0.0000000000000000  1.7349141199999991  56.4676886236687139
>   Ta  0.0000000000000000  1.7349141199999991  44.7301070636687257
>   Ta  0.0000000000000000  1.7349141199999991  32.9925255036687162
>   Ta  0.0000000000000000  1.7349141199999991  21.2549439436687280
>   Ta  0.0000000000000000  1.7349141199999991 9.5173623836687113
>   Ta  0.0000000000000000  0.0000000000000000  59.4020840136687056
>   Ta  0.0000000000000000  0.0000000000000000  47.6645024536687103
>   Ta  0.0000000000000000  0.0000000000000000  35.9269208936687150
>   Ta  0.0000000000000000  0.0000000000000000  24.1893393336687126
>   Ta  0.0000000000000000  0.0000000000000000  12.4517577736687173
> K_POINTS {automatic}
>  9 9 1  1 1 1
>
> Regards,
> Pacome
> Ph.D. Candidate
> Computational Condensed Matter Physics
> University of Cape Town (UCT), South Africa
>
>
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