Dear experts,
I am attempting to perform an scf calculation on a semi-infinite slab of
ferromagnetic cobalt surrounded by a vacuum with an electric field applied
perpendicular to the magnetisation, out-of-plane.
I am struggling to get convergence in the scf cycle. I achieved satisfactory
results using the same geometry and k-points without the field.
I have attempted to run it with ecutwfc = 30, and ecutrho at its default value.
Now I am attempting ecutwfc = 46, ecutrho = 238 (as recommended in the header
of the pseudopotential file).
I find in both cases the total energy and Harris-Foulkes estimate are usually
negative, and the estimated scf accuracy is very large, for each cycle.
The runtime for larger ecutwfc and ecutrho, is much longer.
Is there something I'm doing wrong, or do I need to alter my expectations of
runtime? Please see input file below.
I am running the code with MPI, on 4 cores. At 12 iterations, the CPU time is
24737.9 secs, the total energy is -377.46347734 Ry, the Harris-Foulkes estimate
is -1293.19368730 Ry and the estimated scf accuracy is < 3322.28583637 Ry. I
have also noticed the "Adding external electric field" block is duplicated on
each cycle, though I suspect that's normal.
Many thanks
Alex Durie
PhD student
The Open University
United Kingdom
&control
calculation='scf'
restart_mode='from_scratch',
pseudo_dir = '/home/alex/QE/pslibrary.1.0.0/pz/PSEUDOPOTENTIALS/',
outdir='./'
prefix='co'
tefield = .true.
dipfield = .true.
/
&system
ibrav = 8,
celldm(1) =4.82388,
celldm(2) =8.,
celldm(3) =1.,
nat= 5,
ntyp= 1,
ecutwfc = 46.0
ecutrho = 238.0
nspin = 2
occupations='smearing', smearing='cold', degauss=0.02
starting_magnetization = -1
nbnd = 45
edir = 2
emaxpos = 0.41
eopreg = 0.59
eamp = 0.000243
/
&electrons
electron_maxstep = 500
diagonalization='cg'
conv_thr = 1.0e-6
mixing_beta = 0.3
/
ATOMIC_SPECIES
Co 58.933195 Co.pz<http://Co.pz>-n-kjpaw_psl.1.0.0.UPF<http://psl.1.0.0.UPF>
ATOMIC_POSITIONS {bohr}
Co 0.0000000 0.0000000 0.000000
Co 2.4119400 3.4110000 2.411940
Co 0.0000000 6.8220000 0.000000
Co 2.4119400 10.2330000 2.411940
Co 0.0000000 13.6440000 0.000000
K_POINTS {automatic}
16 2 16 0 0 0
_______________________________________________
users mailing list
[email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
