<div dir="auto">I wouldn't call an oxide of Plutonium "simple"... My guess is that it becomes metallic in simple DFT, try to treat it as such, by setting occupations="smearing"<div dir="auto"><br></div><div dir="auto">Cheers<br><br><div data-smartmail="gmail_signature" dir="auto">-- <br>Lorenzo Paulatto</div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 30 Jul 2020, 18:44 Sergei Butorin, <<a href="mailto:sergei.butorin@physics.uu.se">sergei.butorin@physics.uu.se</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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<p class="MsoNormal">I use QE 6.4.1 and have encountered a problem of pure or no-convergence in scf runs for simple actinide compounds. For example, for PuO2, I get quick convergence for a primitive cell but for a conventional unit cell the convergence to ‘poor’
conv_thr=1.1d-6 is reached only after 560 iterations with the same parameters and pseudos in the input file (see below):<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">&control<u></u><u></u></p>
<p class="MsoNormal">Â calculation = 'scf'<u></u><u></u></p>
<p class="MsoNormal">Â verbosity='high'<u></u><u></u></p>
<p class="MsoNormal">Â prefix = 'system'<u></u><u></u></p>
<p class="MsoNormal">Â pseudo_dir = '/My_input/PuO2/'<u></u><u></u></p>
<p class="MsoNormal">Â outdir = './Out'<u></u><u></u></p>
<p class="MsoNormal">Â wfcdir = 'undefined'<u></u><u></u></p>
<p class="MsoNormal">Â tstress = .false.<u></u><u></u></p>
<p class="MsoNormal">Â tprnfor = .false.<u></u><u></u></p>
<p class="MsoNormal">/<u></u><u></u></p>
<p class="MsoNormal">&system<u></u><u></u></p>
<p class="MsoNormal">Â Â Â ibrav = 0<u></u><u></u></p>
<p class="MsoNormal">Â A =Â Â Â 5.39819<u></u><u></u></p>
<p class="MsoNormal">   nat  = 12<u></u><u></u></p>
<p class="MsoNormal">   ntyp = 2<u></u><u></u></p>
<p class="MsoNormal">Â noncolin = .false.<u></u><u></u></p>
<p class="MsoNormal">Â lspinorb = .false.<u></u><u></u></p>
<p class="MsoNormal">Â ecutwfc = 50<u></u><u></u></p>
<p class="MsoNormal">Â ecutrho = 400<u></u><u></u></p>
<p class="MsoNormal">Â occupations = 'fixed'<u></u><u></u></p>
<p class="MsoNormal"> nspin = 1<u></u><u></u></p>
<p class="MsoNormal">/<u></u><u></u></p>
<p class="MsoNormal">&electrons<u></u><u></u></p>
<p class="MsoNormal">Â conv_thr = 1.1d-6<u></u><u></u></p>
<p class="MsoNormal">Â mixing_beta = 0.3<u></u><u></u></p>
<p class="MsoNormal">Â electron_maxstep = 2000<u></u><u></u></p>
<p class="MsoNormal">Â startingwfc = 'atomic+random'<u></u><u></u></p>
<p class="MsoNormal">Â diagonalization = 'david'<u></u><u></u></p>
<p class="MsoNormal">/<u></u><u></u></p>
<p class="MsoNormal">&ions<u></u><u></u></p>
<p class="MsoNormal">/<u></u><u></u></p>
<p class="MsoNormal">ATOMIC_SPECIES<u></u><u></u></p>
<p class="MsoNormal">Pu  239.0522     Pu.pbe-spfn-rrkjus_psl.1.0.0.UPF<u></u><u></u></p>
<p class="MsoNormal">OÂ Â 15.9994Â Â Â Â Â Â Â O.pbe-n-rrkjus_psl.1.0.0.UPF<u></u><u></u></p>
<p class="MsoNormal">CELL_PARAMETERS alat<u></u><u></u></p>
<p class="MsoNormal">Â 1.000000000000000Â Â 0.000000000000000Â Â 0.000000000000000 <u></u>
<u></u></p>
<p class="MsoNormal">Â Â 0.000000000000000Â Â 1.000000000000000Â Â 0.000000000000000 <u></u>
<u></u></p>
<p class="MsoNormal">Â Â 0.000000000000000Â Â 0.000000000000000Â Â 1.000000000000000 <u></u>
<u></u></p>
<p class="MsoNormal">ATOMIC_POSITIONS crystal<u></u><u></u></p>
<p class="MsoNormal">Pu  0.000000000000000  0.000000000000000  0.000000000000000
<u></u><u></u></p>
<p class="MsoNormal">Pu  0.000000000000000  0.500000000000000  0.500000000000000
<u></u><u></u></p>
<p class="MsoNormal">Pu  0.500000000000000  0.000000000000000  0.500000000000000
<u></u><u></u></p>
<p class="MsoNormal">Pu  0.500000000000000  0.500000000000000  0.000000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.250000000000000Â Â 0.250000000000000Â Â 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.750000000000000Â Â 0.250000000000000Â Â 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.750000000000000Â Â 0.750000000000000Â Â 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.250000000000000Â Â 0.750000000000000Â Â 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.250000000000000Â Â 0.250000000000000Â Â 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.750000000000000Â Â 0.250000000000000Â Â 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.250000000000000Â Â 0.750000000000000Â Â 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal">Â OÂ Â 0.750000000000000Â Â 0.750000000000000Â Â 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal">K_POINTS automatic<u></u><u></u></p>
<p class="MsoNormal">2Â 2Â 2Â 1Â 1Â 1 <u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">Things I have tried to improve the situation but without success:<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">1. Significantly increasing ecutwfc and ecutrho values and keeping the 10-12 ratio for US pseudos.<u></u><u></u></p>
<p class="MsoNormal">2. Using NC pseudos both from the sg15 collection and harder TM pseudos with smaller rc with appropriate ecutwfc and ecutrho values in my pw.x input.<u></u><u></u></p>
<p class="MsoNormal">3. Smaller mixing-beta down to 0.1.<u></u><u></u></p>
<p class="MsoNormal">4. Different mixing_mode (e.g. 'local-TF').<u></u><u></u></p>
<p class="MsoNormal">5. Different diagonalization ('cg').<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">No wonder that in case of a supercell, the convergence value goes only down to a few Ry at best. The occupations = 'smearing' option does not help either.<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">Similar problems I have encoutered for UO2, although I have not investigated that case in detail.<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">My question is whether QE (pw.x) is generally so bad in handling the f-element systems or something is really wrong on my side.<u></u><u></u></p>
<p class="MsoNormal"><u></u>Â <u></u></p>
<p class="MsoNormal">Dr. Sergei Butorin<u></u><u></u></p>
<p class="MsoNormal">Uppsala University<u></u><u></u></p>
<p class="MsoNormal">Sweden<u></u><u></u></p>
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