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 <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 > <[email protected]> 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 > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
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