<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
Hello all,
<p>I have stumbled on a problem that is very frustrating and cannot
figure out what is happening. I am trying to do a vc-relax of a
rather large structure 115 atoms. It constits of
3-SrRuO3/7-PbTiO3/3-SrTiO3/7-PbTiO3/3-SrRuO3. The numbers in front
of the materials represent the number of unit cells of each
material. The structure is 1x1x23. I have tried both with vacuum
on either side (about 15 A because if I add more then the FFT
limit is reached and I get that error) and in super cell
configuration (i.e. no vacuum) but the same thing happens:</p>
<p>The calculation starts and the first scf step converges in 240
iterations. I know it is a large number but the structure is also
large and I have seen that this is quite common for these cases. I
may be wrong thou... The starting charge is 951.8694,
renormalised to 952.0000. All is good and the first step
converges. Then in the second step starts the weird part:</p>
<p>extrapolated charge 991.00311, renormalised to 952.00000</p>
<p>Then it tries to perform the first scf step and the calculation
dies with the: <br>
</p>
<p>Error in c_bands(1):</p>
<p>too many bands are not converged</p>
<p>I do not understand what is happening because I have succesfully
relaxed slightly smaller but similar structures:
3-SrRuO3/7-PbTiO3/3-SrTiO3/3-SrRuO3 and
3-SrRuO3/7-PbTiO3/3-SrRuO3. These two I relaxed with 15A of vacuum
on either side.</p>
<p><br>
</p>
<p>I am using ultrasoft PBE PPs. <br>
</p>
<p>Here is the input I used:</p>
<p><br>
</p>
<p>&control<br>
calculation = 'vc-relax'<br>
restart_mode = 'from_scratch'<br>
prefix = '10Fd-3i-10Fd-slab'<br>
disk_io = 'low'<br>
tstress = .true.<br>
tprnfor = .true.<br>
etot_conv_thr = 1.e-4<br>
forc_conv_thr = 1.e-4<br>
verbosity = 'high'<br>
pseudo_dir = '../pp/pbe-US/'<br>
outdir = '10Fd-3i-10Fd-slab'<br>
nstep = 600<br>
/<br>
<br>
&system<br>
ibrav = 6<br>
celldm(1) = 7.37937998548<br>
celldm(3) = 28.8910838525<br>
nat = 115<br>
ntyp = 5<br>
ecutwfc = 60.<br>
ecutrho = 480.<br>
occupations = 'smearing'<br>
degauss = 0.01<br>
smearing = 'gaussian'<br>
/<br>
<br>
&electrons<br>
diagonalization = 'david'<br>
mixing_beta = 0.1<br>
mixing_mode = 'local-TF'<br>
conv_thr = 1.e-8<br>
scf_must_converge = .false.<br>
electron_maxstep = 400<br>
/<br>
<br>
&ions<br>
ion_dynamics = 'bfgs'<br>
/<br>
<br>
&cell<br>
cell_dynamics = 'bfgs'<br>
/<br>
<br>
ATOMIC_SPECIES<br>
Pb 1 Pb.pbe-dn-rrkjus_psl.0.2.2.UPF<br>
Ti 1 Ti.pbe-spn-rrkjus_psl.1.0.0.UPF<br>
O 1 O.pbe-n-rrkjus_psl.0.1.UPF<br>
Sr 1 Sr.pbe-spn-rrkjus_psl.1.0.0.UPF<br>
Ru 1 Ru.pbe-n-van.UPF<br>
<br>
ATOMIC_POSITIONS {angstrom}<br>
Sr 0.00000000000000 0.00000000000000 0.00000000000000<br>
O 1.95250000000000 1.95250000000000 0.00000000000000<br>
Ru 1.95250000000000 1.95250000000000 1.95250000000000<br>
O 0.00000000000000 1.95250000000000 1.95250000000000<br>
O 1.95250000000000 0.00000000000000 1.95250000000000<br>
Sr 0.00000000000000 0.00000000000000 3.90500000000000<br>
O 1.95250000000000 1.95250000000000 3.90500000000000<br>
Ru 1.95250000000000 1.95250000000000 5.85750000000000<br>
O 0.00000000000000 1.95250000000000 5.85750000000000<br>
O 1.95250000000000 0.00000000000000 5.85750000000000<br>
Sr 0.00000000000000 0.00000000000000 7.81000000000000<br>
O 1.95250000000000 1.95250000000000 7.81000000000000<br>
Ru 1.95250000000000 1.95250000000000 9.76250000000000<br>
O 0.00000000000000 1.95250000000000 9.76250000000000<br>
O 1.95250000000000 0.00000000000000 9.76250000000000<br>
Pb 0.00000000000000 0.00000000000000 11.7202344916000<br>
O 1.95250000000000 1.95250000000000 12.1688551695000<br>
Ti 1.95250000000000 1.95250000000000 13.9438177707000<br>
O 0.00000000000000 1.95250000000000 14.2579079188000<br>
O 1.95250000000000 0.00000000000000 14.2579079188000<br>
Pb 0.00000000000000 0.00000000000000 15.8398546661000<br>
O 1.95250000000000 1.95250000000000 16.2884753441000<br>
Ti 1.95250000000000 1.95250000000000 18.0634379452000<br>
O 0.00000000000000 1.95250000000000 18.3775280934000<br>
O 1.95250000000000 0.00000000000000 18.3775280934000<br>
Pb 0.00000000000000 0.00000000000000 19.9594748407000<br>
O 1.95250000000000 1.95250000000000 20.4080955187000<br>
Ti 1.95250000000000 1.95250000000000 22.1830581198000<br>
O 0.00000000000000 1.95250000000000 22.4971482679000<br>
O 1.95250000000000 0.00000000000000 22.4971482679000<br>
Pb 0.00000000000000 0.00000000000000 24.0790950152000<br>
O 1.95250000000000 1.95250000000000 24.5277156932000<br>
Ti 1.95250000000000 1.95250000000000 26.3026782943000<br>
O 0.00000000000000 1.95250000000000 26.6167684425000<br>
O 1.95250000000000 0.00000000000000 26.6167684425000<br>
Pb 0.00000000000000 0.00000000000000 28.1987151898000<br>
O 1.95250000000000 1.95250000000000 28.6473358678000<br>
Ti 1.95250000000000 1.95250000000000 30.4222984689000<br>
O 0.00000000000000 1.95250000000000 30.7363886171000<br>
O 1.95250000000000 0.00000000000000 30.7363886171000<br>
Pb 0.00000000000000 0.00000000000000 32.3183353644000<br>
O 1.95250000000000 1.95250000000000 32.7669560423000<br>
Ti 1.95250000000000 1.95250000000000 34.5419186435000<br>
O 0.00000000000000 1.95250000000000 34.8560087916000<br>
O 1.95250000000000 0.00000000000000 34.8560087916000<br>
Pb 0.00000000000000 0.00000000000000 36.4379555389000<br>
O 1.95250000000000 1.95250000000000 36.8865762169000<br>
Ti 1.95250000000000 1.95250000000000 38.6615388180000<br>
O 0.00000000000000 1.95250000000000 38.9756289662000<br>
O 1.95250000000000 0.00000000000000 38.9756289662000<br>
Sr 0.00000000000000 0.00000000000000 40.5523412219000<br>
O 1.95250000000000 1.95250000000000 40.5523412219000<br>
Ti 1.95250000000000 1.95250000000000 42.5048412219000<br>
O 0.00000000000000 1.95250000000000 42.5048412219000<br>
O 1.95250000000000 0.00000000000000 42.5048412219000<br>
Sr 0.00000000000000 0.00000000000000 44.4573412219000<br>
O 1.95250000000000 1.95250000000000 44.4573412219000<br>
Ti 1.95250000000000 1.95250000000000 46.4098412219000<br>
O 0.00000000000000 1.95250000000000 46.4098412219000<br>
O 1.95250000000000 0.00000000000000 46.4098412219000<br>
Sr 0.00000000000000 0.00000000000000 48.3623412219000<br>
O 1.95250000000000 1.95250000000000 48.3623412219000<br>
Ti 1.95250000000000 1.95250000000000 50.3148412219000<br>
O 0.00000000000000 1.95250000000000 50.3148412219000<br>
O 1.95250000000000 0.00000000000000 50.3148412219000<br>
Pb 0.00000000000000 0.00000000000000 52.2725757135000<br>
O 1.95250000000000 1.95250000000000 52.7211963915000<br>
Ti 1.95250000000000 1.95250000000000 54.4961589926000<br>
O 0.00000000000000 1.95250000000000 54.8102491407000<br>
O 1.95250000000000 0.00000000000000 54.8102491407000<br>
Pb 0.00000000000000 0.00000000000000 56.3921958880000<br>
O 1.95250000000000 1.95250000000000 56.8408165660000<br>
Ti 1.95250000000000 1.95250000000000 58.6157791671000<br>
O 0.00000000000000 1.95250000000000 58.9298693153000<br>
O 1.95250000000000 0.00000000000000 58.9298693153000<br>
Pb 0.00000000000000 0.00000000000000 60.5118160626000<br>
O 1.95250000000000 1.95250000000000 60.9604367406000<br>
Ti 1.95250000000000 1.95250000000000 62.7353993417000<br>
O 0.00000000000000 1.95250000000000 63.0494894899000<br>
O 1.95250000000000 0.00000000000000 63.0494894899000<br>
Pb 0.00000000000000 0.00000000000000 64.6314362372000<br>
O 1.95250000000000 1.95250000000000 65.0800569151000<br>
Ti 1.95250000000000 1.95250000000000 66.8550195163000<br>
O 0.00000000000000 1.95250000000000 67.1691096644000<br>
O 1.95250000000000 0.00000000000000 67.1691096644000<br>
Pb 0.00000000000000 0.00000000000000 68.7510564117000<br>
O 1.95250000000000 1.95250000000000 69.1996770897000<br>
Ti 1.95250000000000 1.95250000000000 70.9746396908000<br>
O 0.00000000000000 1.95250000000000 71.2887298390000<br>
O 1.95250000000000 0.00000000000000 71.2887298390000<br>
Pb 0.00000000000000 0.00000000000000 72.8706765863000<br>
O 1.95250000000000 1.95250000000000 73.3192972643000<br>
Ti 1.95250000000000 1.95250000000000 75.0942598654000<br>
O 0.00000000000000 1.95250000000000 75.4083500135000<br>
O 1.95250000000000 0.00000000000000 75.4083500135000<br>
Pb 0.00000000000000 0.00000000000000 76.9902967608000<br>
O 1.95250000000000 1.95250000000000 77.4389174388000<br>
Ti 1.95250000000000 1.95250000000000 79.2138800399000<br>
O 0.00000000000000 1.95250000000000 79.5279701881000<br>
O 1.95250000000000 0.00000000000000 79.5279701881000<br>
Sr 0.00000000000000 0.00000000000000 81.1046824438000<br>
O 1.95250000000000 1.95250000000000 81.1046824438000<br>
Ru 1.95250000000000 1.95250000000000 83.0571824438000<br>
O 0.00000000000000 1.95250000000000 83.0571824438000<br>
O 1.95250000000000 0.00000000000000 83.0571824438000<br>
Sr 0.00000000000000 0.00000000000000 85.0096824438000<br>
O 1.95250000000000 1.95250000000000 85.0096824438000<br>
Ru 1.95250000000000 1.95250000000000 86.9621824438000<br>
O 0.00000000000000 1.95250000000000 86.9621824438000<br>
O 1.95250000000000 0.00000000000000 86.9621824438000<br>
Sr 0.00000000000000 0.00000000000000 88.9146824438000<br>
O 1.95250000000000 1.95250000000000 88.9146824438000<br>
Ru 1.95250000000000 1.95250000000000 90.8671824438000<br>
O 0.00000000000000 1.95250000000000 90.8671824438000<br>
O 1.95250000000000 0.00000000000000 90.8671824438000<br>
<br>
K_POINTS {automatic}<br>
3 3 1 0 0 0<br>
<br>
</p>
<p>Regards,</p>
<p><br>
</p>
<p>Lucian<br>
</p>
<div class="moz-signature">-- <br>
<b>Dr. Lucian Dragos Filip</b><br>
National Institute of Materials Physics<br>
Atomistilor str. 405A, PO Box MG. 7<br>
Magurele, 077125<br>
Bucharest, Romania<br>
E-mail: <url><a class="moz-txt-link-abbreviated
moz-txt-link-freetext" href="mailto:lucian.filip@infim.ro">lucian.filip@infim.ro</a></url><br>
Website: <url><a class="moz-txt-link-freetext"
href="https://lucianfilip.wordpress.com/">https://lucianfilip.wordpress.com/</a></url><br>
</div>
</body>
</html>