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<font face="Courier New, Courier, monospace">Dear All,<br>
<br>
I've been practicing some basic calculations with an external
electric field added. I was attempting to calculate the relaxation
of 6% strained silicene for amplitudes between -1 and 1 V/A
(eamp). Runs with eamp between -1 and 0.3 V/A were successful,
however, anything above did not converge. I've tried higher
ecutwfc and ecutrho (up to 100 and 100 Ry, respectively), I've
changed the k-point mesh, I've used mixing_beta between 0.1-0.7,
I've changed the diagonalization method and the mixing_mode, I've
tried different pseudopotentials. Still, nothing helped. Reducing
london_rcut allowed the conversion for 0.4 V/A, however, it had no
effect for 0.5 V/A and above. <br>
<br>
I don't understand why, but the value of eamp seems to be the
problem. If I reduce </font><font face="Courier New, Courier,
monospace"><font face="Courier New, Courier, monospace">eamp</font>,
scf will converge, and more perplexingly if I change the sign of
the amplitude, scf will also converge. My input for 0.5 V/A is
given below.<br>
<br>
Regards,<br>
Maciej Szary<br>
PhD student,<br>
Institute of Physics,<br>
Poznan University of Technology<br>
<br>
<br>
&control<br>
calculation='relax'<br>
prefix='T1',<br>
pseudo_dir='$pseudo_dir'<br>
outdir = 'files/',<br>
wf_collect=.true.<br>
etot_conv_thr=1.0D-5<br>
forc_conv_thr=1.0D-4<br>
tefield=.true.<br>
dipfield=.true.<br>
/<br>
&system<br>
ibrav= 4,<br>
a=3.8448<br>
c=30<br>
nat= 2,<br>
ntyp= 1,<br>
ecutwfc = 55,<br>
ecutrho=550,<br>
occupations= 'smearing',<br>
smearing='gauss',<br>
degauss= 0.0001<br>
assume_isolated = '2D'<br>
<br>
lspinorb=.true.,<br>
noncolin=.true.,<br>
starting_spin_angle=.true.<br>
<br>
vdw_corr='DFT-D'<br>
london_s6=0.75<br>
london_rcut=15.00<br>
<br>
edir=3<br>
eamp=0.009723453<br>
eopreg=0.05<br>
emaxpos=0.85<br>
/<br>
&electrons<br>
electron_maxstep = 150<br>
conv_thr= 1.0d-7<br>
diagonalization='cg'<br>
mixing_beta=0.5<br>
mixing_mode='local-TF'<br>
scf_must_converge=.false.<br>
/ <br>
&ions<br>
ion_dynamics='bfgs'<br>
/ <br>
ATOMIC_SPECIES<br>
Si 28.0855 Si.rel-pbe-n-nc.UPF<br>
ATOMIC_POSITIONS crystal<br>
Si -0.333333300 0.333333330 0.579899915 0 0 1<br>
Si 0.000000000 0.000000000 0.562100085 0 0 1<br>
K_POINTS automatic<br>
12 12 1 0 0 0<br>
</font>
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