[QE-users] SCF calculations on WN supercell not converging

Mattia Angeli mangeli at sissa.it
Fri Jun 19 11:26:43 CEST 2020


Il 2020-06-19 10:15 Andrea Urru ha scritto:
> Dear Coralie,
> 
> the issue you are facing is most likely due to the W pseudopotential,
> which gives convergence issues if used in slab systems
> with vacuum space, as reported here:
> https://dalcorso.github.io/pslibrary/PP_list.html
> 
> The behavior you describe might be due to a ghost state, but I am not
> deeply expert in pseudopotentials and I cannot swear.
> I would suggest you to try a different pseudopotential. If you wish to
> use Ultrasoft pseudopotentials you may try the one from
> Pslibrary 0.3.1.
> 
> Best regards,
> 
> Andrea Urru
> 
> Ph. D. Student in Condensed Matter
> SISSA - Trieste (Italy)
> 
>> Il giorno 17 giu 2020, alle ore 23:31, Coralie Khabbaz
>> <khabbaz.coralie at gmail.com> ha scritto:
>> 
>> Hello,
>> 
>> I am doing an scf calculation on a tungsten nitride (WN) slab
>> (catalyst), with a methane molecule 5 Angstrom away from the
>> surface. The energy values are not converging, even after 533
>> iterations. The energy values are very negative, and then they
>> increase to a positive value then decrease a lot again. Before
>> building the supercell, I had a WN unit cell with 433 K-points.
>> Then, I built the super cell by using a scaling of 333 and miller
>> indices of 100. I tried using K points of 111 and 222 for my super
>> cell, but the calculations didn't converge for both.
>> 
>> This is the input file I am using:
>> 
>> &CONTROL
>> calculation  = "scf"
>> max_seconds  =  1.72800e+05
>> pseudo_dir   =
>> "/home/coralee/projects/def-jkopysci/coralee/.pseudopot"
>> restart_mode = "from_scratch"
>> /
>> 
>> &SYSTEM
>> a                         =  1.24907e+01
>> angle1(1)                 =  0.00000e+00
>> angle1(2)                 =  0.00000e+00
>> angle2(1)                 =  0.00000e+00
>> angle2(2)                 =  0.00000e+00
>> b                         =  1.34803e+01
>> c                         =  2.52767e+01
>> cosab                     =  6.12323e-17
>> cosac                     =  6.12323e-17
>> cosbc                     = -1.85547e-01
>> degauss                   =  1.00000e-02
>> ecutrho                   =  4.50000e+02
>> ecutwfc                   =  5.00000e+01
>> ibrav                     = 14
>> nat                       = 113
>> nspin                     = 2
>> ntyp                      = 4
>> occupations               = "smearing"
>> smearing                  = "gaussian"
>> starting_magnetization(1) =  2.00000e-01
>> starting_magnetization(2) =  6.00000e-01
>> starting_magnetization(3) =  0.00000e+00
>> starting_magnetization(4) =  0.00000e+00
>> /
>> 
>> &ELECTRONS
>> conv_thr         =  1.00000e-06
>> diagonalization  = "david"
>> electron_maxstep = 528
>> mixing_beta      =  4.00000e-01
>> startingpot      = "atomic"
>> startingwfc      = "atomic+random"
>> /
>> 
>> K_POINTS {automatic}
>> 4  4  2  0 0 0
>> 
>> ATOMIC_SPECIES
>> N      14.00674  N.pbe-n-rrkjus_psl.1.0.0.UPF
>> W     183.84000  W.pbe-spn-rrkjus_psl.1.0.0.UPF
>> C      12.01070  C.pbe-n-rrkjus_psl.1.0.0.UPF
>> H       1.00794  H.pbe-rrkjus_psl.1.0.0.UPF
>> 
>> ATOMIC_POSITIONS {angstrom}
>> N       2.481849   0.418242  14.837784
>> N       6.645429   0.418242  14.837784
>> N      10.809008   0.418242  14.837784
>> N       2.481849   4.911686  14.837784
>> N       6.645429   4.911686  14.837784
>> N      10.809008   4.911686  14.837784
>> N       2.481849   9.405131  14.837784
>> N       6.645429   9.405131  14.837784
>> N      10.809008   9.405131  14.837784
>> W       2.481849   2.628097  14.748648
>> W       6.645429   2.628097  14.748648
>> W      10.809008   2.628097  14.748648
>> W       2.481849   7.121541  14.748648
>> W       6.645429   7.121541  14.748648
>> W      10.809008   7.121541  14.748648
>> W       2.481849  -1.865347  14.748648
>> W       6.645429  -1.865347  14.748648
>> W      10.809008  -1.865347  14.748648
>> N       0.400059   3.110895  14.468179
>> N       4.563639   3.110895  14.468179
>> N       8.727218   3.110895  14.468179
>> N       0.400059   7.604339  14.468179
>> N       4.563639   7.604339  14.468179
>> N       8.727218   7.604339  14.468179
>> N       0.400059  -1.382549  14.468179
>> N       4.563639  -1.382549  14.468179
>> N       8.727218  -1.382549  14.468179
>> W       0.400059   0.783425  14.415413
>> W       4.563639   0.783425  14.415413
>> W       8.727218   0.783425  14.415413
>> W       0.400059   5.276869  14.415413
>> W       4.563639   5.276869  14.415413
>> W       8.727218   5.276869  14.415413
>> W       0.400059   9.770314  14.415413
>> W       4.563639   9.770314  14.415413
>> W       8.727218   9.770314  14.415413
>> N       2.481849   3.081849  12.630078  0 0 0
>> N       6.645429   3.081849  12.630078  0 0 0
>> N      10.809008   3.081849  12.630078  0 0 0
>> N       2.481849   7.575293  12.630078  0 0 0
>> N       6.645429   7.575293  12.630078  0 0 0
>> N      10.809008   7.575293  12.630078  0 0 0
>> N       2.481849  -1.411595  12.630078  0 0 0
>> N       6.645429  -1.411595  12.630078  0 0 0
>> N      10.809008  -1.411595  12.630078  0 0 0
>> W       2.481849   0.798260  12.540942  0 0 0
>> W       6.645429   0.798260  12.540942  0 0 0
>> W      10.809008   0.798260  12.540942  0 0 0
>> W       2.481849   5.291704  12.540942  0 0 0
>> W       6.645429   5.291704  12.540942  0 0 0
>> W      10.809008   5.291704  12.540942  0 0 0
>> W       2.481849   9.785148  12.540942  0 0 0
>> W       6.645429   9.785148  12.540942  0 0 0
>> W      10.809008   9.785148  12.540942  0 0 0
>> N       0.400059   1.281057  12.260473  0 0 0
>> N       4.563639   1.281057  12.260473  0 0 0
>> N       8.727218   1.281057  12.260473  0 0 0
>> N       0.400059   5.774502  12.260473  0 0 0
>> N       4.563639   5.774502  12.260473  0 0 0
>> N       8.727218   5.774502  12.260473  0 0 0
>> N       0.400059  10.267946  12.260473  0 0 0
>> N       4.563639  10.267946  12.260473  0 0 0
>> N       8.727218  10.267946  12.260473  0 0 0
>> W       0.400059   3.447032  12.207706  0 0 0
>> W       4.563639   3.447032  12.207706  0 0 0
>> W       8.727218   3.447032  12.207706  0 0 0
>> W       0.400059   7.940476  12.207706  0 0 0
>> W       4.563639   7.940476  12.207706  0 0 0
>> W       8.727218   7.940476  12.207706  0 0 0
>> W       0.400059  -1.046412  12.207706  0 0 0
>> W       4.563639  -1.046412  12.207706  0 0 0
>> W       8.727218  -1.046412  12.207706  0 0 0
>> N       2.481849   1.252012  10.422372  0 0 0
>> N       6.645429   1.252012  10.422372  0 0 0
>> N      10.809008   1.252012  10.422372  0 0 0
>> N       2.481849   5.745456  10.422372  0 0 0
>> N       6.645429   5.745456  10.422372  0 0 0
>> N      10.809008   5.745456  10.422372  0 0 0
>> N       2.481849  10.238900  10.422372  0 0 0
>> N       6.645429  10.238900  10.422372  0 0 0
>> N      10.809008  10.238900  10.422372  0 0 0
>> W       2.481849   3.461867  10.333236  0 0 0
>> W       6.645429   3.461867  10.333236  0 0 0
>> W      10.809008   3.461867  10.333236  0 0 0
>> W       2.481849   7.955311  10.333236  0 0 0
>> W       6.645429   7.955311  10.333236  0 0 0
>> W      10.809008   7.955311  10.333236  0 0 0
>> W       2.481849  -1.031577  10.333236  0 0 0
>> W       6.645429  -1.031577  10.333236  0 0 0
>> W      10.809008  -1.031577  10.333236  0 0 0
>> N       0.400059   3.944664  10.052766  0 0 0
>> N       4.563639   3.944664  10.052766  0 0 0
>> N       8.727218   3.944664  10.052766  0 0 0
>> N       0.400059   8.438108  10.052766  0 0 0
>> N       4.563639   8.438108  10.052766  0 0 0
>> N       8.727218   8.438108  10.052766  0 0 0
>> N       0.400059  -0.548780  10.052766  0 0 0
>> N       4.563639  -0.548780  10.052766  0 0 0
>> N       8.727218  -0.548780  10.052766  0 0 0
>> W       0.400059   1.617195  10.000000  0 0 0
>> W       4.563639   1.617195  10.000000  0 0 0
>> W       8.727218   1.617195  10.000000  0 0 0
>> W       0.400059   6.110639  10.000000  0 0 0
>> W       4.563639   6.110639  10.000000  0 0 0
>> W       8.727218   6.110639  10.000000  0 0 0
>> W       0.400059  10.604083  10.000000  0 0 0
>> W       4.563639  10.604083  10.000000  0 0 0
>> W       8.727218  10.604083  10.000000  0 0 0
>> C      10.809008   2.628097  19.750000
>> H      10.177000   1.997000  20.383000
>> H      11.443000   1.997000  19.117000
>> H      10.177000   3.263000  19.117000
>> H      11.443000   3.263000  20.383000
>> 
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> 
> 
> 
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Dear All,

As Andrea mentioned before, the  PBE-ultrasoft pseudos for W found in 
PSlibrary 1.0.0 are not working for 2D geometries.
However, I had similar convergence issues also using W pseudos taken 
from older versions of PSlibrary (both scalar and fully relativistic), 
especially if lattice relaxation was included in the calculation.

I solved the problem by using the pseudopotentials found here: 
https://www.materialscloud.org/discover/sssp/table/efficiency

best,




Mattia Angeli

Ph. D. Student in Condensed Matter
SISSA - Trieste (Italy)





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