<div dir="auto"><div>edir=1 and 2 are extremely inefficient in parallel. Use edir=3, rotate your slab. Does it converge without field? Also, your choic is a of k-points looks the opposite of correct: you need many points along the field direction. </div><div dir="auto"><br><div data-smartmail="gmail_signature" dir="auto">-- <br>Lorenzo Paulatto<br>Written on a virtual keyboard with real fingers</div><br><div class="gmail_quote" dir="auto"><div dir="ltr">On Sat, 29 Sep 2018, 20:43 Alex.Durie, <<a href="mailto:alex.durie@open.ac.uk">alex.durie@open.ac.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Dear experts,<br>
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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.<br>
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I am struggling to get convergence in the scf cycle. I achieved satisfactory results using the same geometry and k-points without the field.<br>
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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).<br>
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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.<br>
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The runtime for larger ecutwfc and ecutrho, is much longer.<br>
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Is there something I'm doing wrong, or do I need to alter my expectations of runtime? Please see input file below.<br>
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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.<br>
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Many thanks<br>
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Alex Durie<br>
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PhD student<br>
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The Open University<br>
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United Kingdom<br>
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&control<br>
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calculation='scf'<br>
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restart_mode='from_scratch',<br>
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pseudo_dir = '/home/alex/QE/pslibrary.1.0.0/pz/PSEUDOPOTENTIALS/',<br>
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outdir='./'<br>
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prefix='co' <br>
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tefield = .true.<br>
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dipfield = .true.<br>
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/<br>
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&system<br>
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ibrav = 8, <br>
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celldm(1) =4.82388, <br>
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celldm(2) =8., <br>
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celldm(3) =1.,<br>
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nat= 5, <br>
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ntyp= 1,<br>
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ecutwfc = 46.0<br>
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ecutrho = 238.0<br>
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nspin = 2<br>
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occupations='smearing', smearing='cold', degauss=0.02<br>
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starting_magnetization = -1<br>
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nbnd = 45 <br>
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edir = 2<br>
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emaxpos = 0.41<br>
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eopreg = 0.59<br>
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eamp = 0.000243<br>
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/<br>
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&electrons<br>
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electron_maxstep = 500<br>
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diagonalization='cg'<br>
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conv_thr = 1.0e-6<br>
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mixing_beta = 0.3<br>
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/<br>
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ATOMIC_SPECIES<br>
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Co 58.933195 <a href="http://Co.pz" target="_blank" rel="noreferrer">Co.pz</a>-n-kjpaw_<a href="http://psl.1.0.0.UPF" target="_blank" rel="noreferrer">psl.1.0.0.UPF</a>
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ATOMIC_POSITIONS {bohr}<br>
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Co 0.0000000 0.0000000 0.000000<br>
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Co 2.4119400 3.4110000 2.411940<br>
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Co 0.0000000 6.8220000 0.000000 <br>
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Co 2.4119400 10.2330000 2.411940<br>
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Co 0.0000000 13.6440000 0.000000<br>
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K_POINTS {automatic}<br>
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16 2 16 0 0 0<br>
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