The low structural symmetry leads to inconsistent k points between the input and output of the nscf calculation.

[dsc]

Dear Developer,

I am currently investigating superconductivity in a system with space group P1 and 54 atoms using EPW. I generated a uniform k-mesh using kmesh.pl 2 2 2, which should yield 8 k-points. However, the nscf.out file indicates 20 k-points,
the nscf.in file is as follows:
&CONTROL
calculation = 'nscf',
prefix='Metal',
pseudo_dir = './',
outdir='./tmp',
verbosity = 'high',
/
&SYSTEM
ibrav = 0,
nat = 54,
ntyp = 3,
ecutwfc = 80,
ecutrho = 640,
occupations = 'smearing',
smearing = 'mp',
degauss = 0.010,
input_dft = 'PBESOL',
nbnd = 240
/
&ELECTRONS
electron_maxstep = 800,
diagonalization = 'rmm-davidson',
mixing_mode = 'TF',
mixing_beta = 0.1,
conv_thr = 1.0d-10,
/
ATOMIC_SPECIES

CELL_PARAMETERS (angstrom)

ATOMIC_POSITIONS (crystal)

K_POINTS crystal
8
0.00000000 0.00000000 0.00000000 1.250000e-01
0.00000000 0.00000000 0.50000000 1.250000e-01
0.00000000 0.50000000 0.00000000 1.250000e-01
0.00000000 0.50000000 0.50000000 1.250000e-01
0.50000000 0.00000000 0.00000000 1.250000e-01
0.50000000 0.00000000 0.50000000 1.250000e-01
0.50000000 0.50000000 0.00000000 1.250000e-01
0.50000000 0.50000000 0.50000000 1.250000e-01


and nscf.out gives as follows:
number of k points= 20 Methfessel-Paxton smearing, width (Ry)= 0.0100
cart. coord. in units 2pi/alat
k( 1) = ( 0.0000000 0.0000000 0.0000000), wk = 0.2500000
k( 2) = ( 0.0000000 0.0000000 -0.5000000), wk = 0.0833333
k( 3) = ( 0.0000000 -0.5000000 -0.5000000), wk = 0.0833333
k( 4) = ( -0.5000000 -0.5000000 -0.5000000), wk = 0.2500000
k( 5) = ( -0.5000000 0.0000000 0.0000000), wk = 0.0833333
k( 6) = ( 0.0000000 -0.5000000 0.0000000), wk = 0.0833333
k( 7) = ( -0.5000000 0.0000000 0.5000000), wk = 0.0833333
k( 8) = ( -0.5000000 0.5000000 0.0000000), wk = 0.0833333
k( 9) = ( -0.5000000 0.0000000 0.0000000), wk = 0.0833333
k( 10) = ( 0.0000000 -0.5000000 0.0000000), wk = 0.0833333
k( 11) = ( -0.5000000 0.0000000 0.5000000), wk = 0.0833333
k( 12) = ( -0.5000000 0.5000000 0.0000000), wk = 0.0833333
k( 13) = ( 0.0000000 -0.5000000 0.0000000), wk = 0.0833333
k( 14) = ( 0.0000000 0.0000000 -0.5000000), wk = 0.0833333
k( 15) = ( -0.5000000 0.0000000 0.0000000), wk = 0.0833333
k( 16) = ( 0.0000000 0.0000000 -0.5000000), wk = 0.0833333
k( 17) = ( 0.0000000 -0.5000000 -0.5000000), wk = 0.0833333
k( 18) = ( 0.5000000 0.5000000 0.0000000), wk = 0.0833333
k( 19) = ( 0.0000000 -0.5000000 -0.5000000), wk = 0.0833333
k( 20) = ( 0.5000000 0.0000000 0.5000000), wk = 0.0833333


This will result in the EPW error:
Error in routine wannierize (1):
inconsistent nscf and elph k-grids

Any guidance would be greatly appreciated.

Thank you for your time and support.
Best regards,
Shicong Ding

[stiwari]

Hi Shicong,

You can change the calculation='nscf' to calculation='bands' in your input file. That should solve the problem.

Best regards,
Sabya.