[QE-users] SCF calculations on WN supercell not converging
Lorenzo Paulatto
paulatz at gmail.com
Fri Jun 19 11:36:23 CEST 2020
It may happen in a system with a lot of vacuum that an electrons prefers
to stay in the vacuum, when this happens the SC usually does not
converge (and if it did, it would make no sense). You can check if this
is the case, by plotting the non-converged charge density and see if
there is anything in the vacuum.
Possible solutions include:
1) reducing the vacuum region
2) using 2D-specific corrections can make the vacuum less appealing
(this usually allows you to use less vacuum as well)
3) changing the structure of the slab, i.e. adding a strongly electro-
negative ion to capture the excess charge
4) set "scf_must_converge" to false, and hope that the problem goes
away after relax
cheers
On 6/17/20 11:31 PM, Coralie Khabbaz wrote:
> 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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--
Lorenzo Paulatto - Paris
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