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

[Pacome NGUIMEYA]

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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