Dear Sohail Ahmad,
Which convergence do you mean: Electronic self-consistency or the
geometry (ions and cell)? About the former I do not know much - I tried
your input, with few k points it seems to converge; only that the value of
'degauss' is quite small - but some notes on the input otherwise:
You have chosen a _very_ high cut-off 'ecutwfc'; considering that even
if you are doing the relaxation of the cell and thus need a well converged
stress tensor, this value look very high. Your system looks
nearly-hexagonal but is not just quite - is this intentional? If you
decide to go precisely hexagonal cell I would recommend using a k point
set containing the later Gamma-point (shift "0 0" of the mesh along the
first two reciprocal directions), as the original Monkhorst-Pack k point
mesh (corresponding to "1 1") yields a lower symmetry than the hexagonal
three-fold one (discussed eg in the Appendix of my PhD thesis). But what I
would change in any case is to use the keyword 'cell_dofree' in your input
in order to avoid that the cell vector is modified between the layers, or
along the [001] direction.
Greetings from Montrouge/France,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Sat, 5 Dec 2015, Sohail Ahmad wrote:
Dear QE users
I am finding difficulty in getting convergence while optimizing structure by vc-relax
using fully relativistic potential.
Is there any special trick while using fully relativistic pseudo potential ?
---------------------------------------------------------------------------
&control
calculation = 'vc-relax',
restart_mode = 'from_scratch',
prefix = 'PtS',
pseudo_dir = '/home/sohail/Espresso/espresso-5.0.1/pseudo',
outdir = './OUT',
/
&system
ibrav = 0,
nat = 3, ntyp = 2,
ecutwfc = 150,
ecutrho = 600,
nbnd = 25,
occupations = 'smearing', smearing = 'gaussian', degauss = 0.001,
noncolin = .true.,
lspinorb = .true.,
starting_magnetization(1) = 0.1d0,
/
&electrons
mixing_beta = 0.3,
conv_thr = 1.0d-9,
/
&ions
ion_dynamics = 'bfgs',
/
&cell
cell_dynamics = 'bfgs',
press = 0.d0,
press_conv_thr = 1.2d0,
/
ATOMIC_SPECIES
Pt 195.08 Pt.rel-pbe-n-kjpaw_psl.0.1.UPF
S 32.06 S.rel-pbe-n-kjpaw_psl.0.1.UPF
ATOMIC_POSITIONS angstrom
Pt 0.00000000 0.00000000 0.00000000
S 1.80374872 1.02665089 1.24494264
S -1.80374872 -1.02665089 -1.24494264
CELL_PARAMETERS {hexagon}
3.37036749 5.86580486 0.00000000
-6.81427354 0.03307209 0.00000000
0.00000000 0.00000000 28.34590000
K_POINTS AUTOMATIC
12 12 1 1 1 1
---------------------------------------------------------------------
Sohail Ahmad
King Khalid University
Abha, Saudi Arabia
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