[QE-users] I don't know how to add empty bands and broaden my super cell

Vahid Askarpour vh261281 at dal.ca
Thu Jun 18 02:36:45 CEST 2020


If you have say 20 filled bands, then set nbnd=24. This will set 4 empty bands+the 20 filled bands. The tag is “nbnd" not “nbd”.

The “degauss” tag is explained in the QE online manual. It is the broadening for BZ integration. The default is zero, which is what you have. Try some small value such as degauss=0.005 (in Ry) or higher. For better understanding of degauss and how to set it, see the following link:http://theossrv1.epfl.ch/Main/ElectronicTemperature.

Cheers,
Vahid

On Jun 17, 2020, at 9:25 PM, Coralie Khabbaz <khabbaz.coralie at gmail.com<mailto:khabbaz.coralie at gmail.com>> wrote:

CAUTION: The Sender of this email is not from within Dalhousie.
Hello vahid,

Thank you so much for your answer! As I am performing an scf calculation, nbd is not in my input file (I have pasted my input file at the end). Should I just write nbd=... in the &System part of my input file?
As for the smearing, what do you mean by degauss? Currently, I have specified a gaussian smearing for my file. Is this okay?

This is my input file:
&CONTROL
    calculation  = "scf"
    max_seconds  =  1.72800e+05
    pseudo_dir   = "/Users/coralie/.burai/.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                   =  2.00000e-02
    ecutrho                   =  4.75221e+02
    ecutwfc                   =  5.03902e+01
    ibrav                     = 14
    nat                       = 113
    nspin                     = 2
    ntyp                      = 4
    occupations               = "smearing"
    smearing                  = "fermi-dirac"
    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      =  1.41935e-01
    mixing_mode      = "local-TF"
    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       3.059711   0.418242  14.837784
N       7.223291   0.418242  14.837784
N      11.386870   0.418242  14.837784
N       3.059711   4.911686  14.837784
N       7.223291   4.911686  14.837784
N      11.386870   4.911686  14.837784
N       3.059711   9.405131  14.837784
N       7.223291   9.405131  14.837784
N      11.386870   9.405131  14.837784
W       3.059711   2.628097  14.748648
W       7.223291   2.628097  14.748648
W      11.386870   2.628097  14.748648
W       3.059711   7.121541  14.748648
W       7.223291   7.121541  14.748648
W      11.386870   7.121541  14.748648
W       3.059711  -1.865347  14.748648
W       7.223291  -1.865347  14.748648
W      11.386870  -1.865347  14.748648
N       0.977921   3.110895  14.468179
N       5.141501   3.110895  14.468179
N       9.305080   3.110895  14.468179
N       0.977921   7.604339  14.468179
N       5.141501   7.604339  14.468179
N       9.305080   7.604339  14.468179
N       0.977921  -1.382549  14.468179
N       5.141501  -1.382549  14.468179
N       9.305080  -1.382549  14.468179
W       0.977921   0.783425  14.415413
W       5.141501   0.783425  14.415413
W       9.305080   0.783425  14.415413
W       0.977921   5.276869  14.415413
W       5.141501   5.276869  14.415413
W       9.305080   5.276869  14.415413
W       0.977921   9.770314  14.415413
W       5.141501   9.770314  14.415413
W       9.305080   9.770314  14.415413
N       3.059711   3.081849  12.630078
N       7.223291   3.081849  12.630078
N      11.386870   3.081849  12.630078
N       3.059711   7.575293  12.630078
N       7.223291   7.575293  12.630078
N      11.386870   7.575293  12.630078
N       3.059711  -1.411595  12.630078
N       7.223291  -1.411595  12.630078
N      11.386870  -1.411595  12.630078
W       3.059711   0.798260  12.540942
W       7.223291   0.798260  12.540942
W      11.386870   0.798260  12.540942
W       3.059711   5.291704  12.540942
W       7.223291   5.291704  12.540942
W      11.386870   5.291704  12.540942
W       3.059711   9.785148  12.540942
W       7.223291   9.785148  12.540942
W      11.386870   9.785148  12.540942
N       0.977921   1.281057  12.260473
N       5.141501   1.281057  12.260473
N       9.305080   1.281057  12.260473
N       0.977921   5.774502  12.260473
N       5.141501   5.774502  12.260473
N       9.305080   5.774502  12.260473
N       0.977921  10.267946  12.260473
N       5.141501  10.267946  12.260473
N       9.305080  10.267946  12.260473
W       0.977921   3.447032  12.207706
W       5.141501   3.447032  12.207706
W       9.305080   3.447032  12.207706
W       0.977921   7.940476  12.207706
W       5.141501   7.940476  12.207706
W       9.305080   7.940476  12.207706
W       0.977921  -1.046412  12.207706
W       5.141501  -1.046412  12.207706
W       9.305080  -1.046412  12.207706
N       3.059711   1.252012  10.422372  0 0 0
N       7.223291   1.252012  10.422372  0 0 0
N      11.386870   1.252012  10.422372  0 0 0
N       3.059711   5.745456  10.422372  0 0 0
N       7.223291   5.745456  10.422372  0 0 0
N      11.386870   5.745456  10.422372  0 0 0
N       3.059711  10.238900  10.422372  0 0 0
N       7.223291  10.238900  10.422372  0 0 0
N      11.386870  10.238900  10.422372  0 0 0
W       3.059711   3.461867  10.333236  0 0 0
W       7.223291   3.461867  10.333236  0 0 0
W      11.386870   3.461867  10.333236  0 0 0
W       3.059711   7.955311  10.333236  0 0 0
W       7.223291   7.955311  10.333236  0 0 0
W      11.386870   7.955311  10.333236  0 0 0
W       3.059711  -1.031577  10.333236  0 0 0
W       7.223291  -1.031577  10.333236  0 0 0
W      11.386870  -1.031577  10.333236  0 0 0
N       0.977921   3.944664  10.052766  0 0 0
N       5.141501   3.944664  10.052766  0 0 0
N       9.305080   3.944664  10.052766  0 0 0
N       0.977921   8.438108  10.052766  0 0 0
N       5.141501   8.438108  10.052766  0 0 0
N       9.305080   8.438108  10.052766  0 0 0
N       0.977921  -0.548780  10.052766  0 0 0
N       5.141501  -0.548780  10.052766  0 0 0
N       9.305080  -0.548780  10.052766  0 0 0
W       0.977921   1.617195  10.000000  0 0 0
W       5.141501   1.617195  10.000000  0 0 0
W       9.305080   1.617195  10.000000  0 0 0
W       0.977921   6.110639  10.000000  0 0 0
W       5.141501   6.110639  10.000000  0 0 0
W       9.305080   6.110639  10.000000  0 0 0
W       0.977921  10.604083  10.000000  0 0 0
W       5.141501  10.604083  10.000000  0 0 0
W       9.305080  10.604083  10.000000  0 0 0
C       7.223291   2.628097  19.750000
H       6.590292   1.997000  20.383000
H       7.856291   1.997000  19.117000
H       6.590292   3.263000  19.117000
H       7.856291   3.263000  20.383000



On Wed, 17 Jun 2020 at 19:51, Vahid Askarpour <vh261281 at dal.ca<mailto:vh261281 at dal.ca>> wrote:
Specify nbnd for bands.
For broadening, check the input parameters occupations, smearing, degauss.

Cheers,
Vahid

Vahid Askarpour
Department of physics and atmospheric science
Dalhousie University
Halifax, NS
Canada

On Jun 17, 2020, at 8:44 PM, Coralie Khabbaz <khabbaz.coralie at gmail.com<mailto:khabbaz.coralie at gmail.com>> wrote:

CAUTION: The Sender of this email is not from within Dalhousie.
I am performing an SCF calculation (on a tungsten nitride slab that contains 114 atoms) that is not converging. I was told that I had to add a few empty bands and a broadening. However, I don't know how to do that as I am still a beginner. How do I add empty bands and how do I broaden? Please help!!
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