<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> <u></u></p>
<p class="MsoNormal">&control<u></u><u></u></p>
<p class="MsoNormal"> calculation = 'scf'<u></u><u></u></p>
<p class="MsoNormal"> verbosity='high'<u></u><u></u></p>
<p class="MsoNormal"> prefix = 'system'<u></u><u></u></p>
<p class="MsoNormal"> pseudo_dir = '/My_input/PuO2/'<u></u><u></u></p>
<p class="MsoNormal"> outdir = './Out'<u></u><u></u></p>
<p class="MsoNormal"> wfcdir = 'undefined'<u></u><u></u></p>
<p class="MsoNormal"> tstress = .false.<u></u><u></u></p>
<p class="MsoNormal"> 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"> ibrav = 0<u></u><u></u></p>
<p class="MsoNormal"> A = 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"> noncolin = .false.<u></u><u></u></p>
<p class="MsoNormal"> lspinorb = .false.<u></u><u></u></p>
<p class="MsoNormal"> ecutwfc = 50<u></u><u></u></p>
<p class="MsoNormal"> ecutrho = 400<u></u><u></u></p>
<p class="MsoNormal"> 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"> conv_thr = 1.1d-6<u></u><u></u></p>
<p class="MsoNormal"> mixing_beta = 0.3<u></u><u></u></p>
<p class="MsoNormal"> electron_maxstep = 2000<u></u><u></u></p>
<p class="MsoNormal"> startingwfc = 'atomic+random'<u></u><u></u></p>
<p class="MsoNormal"> 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">O 15.9994 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"> 1.000000000000000 0.000000000000000 0.000000000000000 <u></u>
<u></u></p>
<p class="MsoNormal"> 0.000000000000000 1.000000000000000 0.000000000000000 <u></u>
<u></u></p>
<p class="MsoNormal"> 0.000000000000000 0.000000000000000 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"> O 0.250000000000000 0.250000000000000 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.750000000000000 0.250000000000000 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.750000000000000 0.750000000000000 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.250000000000000 0.750000000000000 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.250000000000000 0.250000000000000 0.750000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.750000000000000 0.250000000000000 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.250000000000000 0.750000000000000 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal"> O 0.750000000000000 0.750000000000000 0.250000000000000
<u></u><u></u></p>
<p class="MsoNormal">K_POINTS automatic<u></u><u></u></p>
<p class="MsoNormal">2 2 2 1 1 1 <u></u><u></u></p>
<p class="MsoNormal"><u></u> <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> <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> <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> <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> <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> <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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