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<div>Indeed, the stress tensor converges poorly with cutoff, and an equation of state with ev.x would be better than vc relax (ie. 7-10 scf calculations at different volumes).</div>
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<div>For all - please, *before* asking a question like this, try the parameters and pseudopotentials suggested by:</div>
<a href="https://www.materialscloud.org/work/tools/qeinputgenerator">https://www.materialscloud.org/work/tools/qeinputgenerator</a>
<div><br>
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<div>Nicola<br>
<br>
<div dir="ltr">Sent from a tiny keyboard... Contact info:
<div>
<div>http://theossrv1.epfl.ch/Main/Contact</div>
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<blockquote type="cite">On 9 Dec 2019, at 09:39, Pietro Bonfà <pietro.bonfa@unipr.it> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr"><span>Dear S. Arash Sheikholeslam,</span><br>
<span></span><br>
<span>your settings for the basis set seem quite low, you should consider increasing these two values:</span><br>
<span></span><br>
<span>ecutwfc = 25.0, ecutrho = 300.0</span><br>
<span></span><br>
<span>You can check this web page https://www.materialscloud.org/discover/sssp/plot/efficiency/Pb to identify the appropriate basis set parameters for the pseudopotential that you are using. The actual values to be used should be converged according to the
specific scientific case that you intend to investigate.</span><br>
<span></span><br>
<span>Reciprocal space sampling should probably also be improved.</span><br>
<span></span><br>
<span>Best regards,</span><br>
<span>Pietro</span><br>
<span></span><br>
<span></span><br>
<span>On 12/8/19 9:54 PM, sarashs wrote:</span><br>
<blockquote type="cite"><span>Hi quantum espresso users,</span><br>
</blockquote>
<blockquote type="cite"><span>I am performing a vc-relax simulation on pb. I have included my input file for your convenience. The problem that I have is that the minimum energy cell is more than 1 Angstrom smaller on each dimension (3.25 Angstrom) while it
should be around 4.95. I am wondering if you can help me figure out why? I have tried increasing the number of K points, ecutwfc and I tried with different degauss values but I was not successful in converging to the right size.</span><br>
</blockquote>
<blockquote type="cite"><span>Is this an xc functional issue? or something else?</span><br>
</blockquote>
<blockquote type="cite"><span>&control</span><br>
</blockquote>
<blockquote type="cite"><span> calculation = "vc-relax" ,</span><br>
</blockquote>
<blockquote type="cite"><span> restart_mode = 'from_scratch' ,</span><br>
</blockquote>
<blockquote type="cite"><span> outdir='$TMP_DIR/' ,</span><br>
</blockquote>
<blockquote type="cite"><span> pseudo_dir = '$PSEUDO_DIR' ,</span><br>
</blockquote>
<blockquote type="cite"><span> disk_io = 'default' ,</span><br>
</blockquote>
<blockquote type="cite"><span> verbosity = 'default' ,</span><br>
</blockquote>
<blockquote type="cite"><span> tstress = .true. ,</span><br>
</blockquote>
<blockquote type="cite"><span> tprnfor = .true. ,</span><br>
</blockquote>
<blockquote type="cite"><span> /</span><br>
</blockquote>
<blockquote type="cite"><span> &system</span><br>
</blockquote>
<blockquote type="cite"><span> ibrav = 2, celldm(1) =4.9505, nat= 1, ntyp= 1,</span><br>
</blockquote>
<blockquote type="cite"><span> ecutwfc = 25.0, ecutrho = 300.0</span><br>
</blockquote>
<blockquote type="cite"><span> occupations='smearing', smearing='gaussian', degauss=0.02</span><br>
</blockquote>
<blockquote type="cite"><span> /</span><br>
</blockquote>
<blockquote type="cite"><span> &electrons</span><br>
</blockquote>
<blockquote type="cite"><span> diagonalization='david'</span><br>
</blockquote>
<blockquote type="cite"><span> conv_thr = 1.0e-8</span><br>
</blockquote>
<blockquote type="cite"><span> mixing_beta = 0.7</span><br>
</blockquote>
<blockquote type="cite"><span> /</span><br>
</blockquote>
<blockquote type="cite"><span>&IONS</span><br>
</blockquote>
<blockquote type="cite"><span> /</span><br>
</blockquote>
<blockquote type="cite"><span> &CELL</span><br>
</blockquote>
<blockquote type="cite"><span> cell_dynamics = 'bfgs',</span><br>
</blockquote>
<blockquote type="cite"><span> press = 1.00 ,</span><br>
</blockquote>
<blockquote type="cite"><span> /</span><br>
</blockquote>
<blockquote type="cite"><span>ATOMIC_SPECIES</span><br>
</blockquote>
<blockquote type="cite"><span> Pb 207.2 Pb.pbe-dn-kjpaw_psl.1.0.0.UPF</span><br>
</blockquote>
<blockquote type="cite"><span>ATOMIC_POSITIONS alat</span><br>
</blockquote>
<blockquote type="cite"><span> Pb 0.0 0.0 0.0</span><br>
</blockquote>
<blockquote type="cite"><span>K_POINTS (automatic)</span><br>
</blockquote>
<blockquote type="cite"><span> 5 5 5 0 0 0</span><br>
</blockquote>
<blockquote type="cite"><span>Best regards,</span><br>
</blockquote>
<blockquote type="cite"><span>S. Arash Sheikholeslam</span><br>
</blockquote>
<blockquote type="cite"><span>_______________________________________________</span><br>
</blockquote>
<blockquote type="cite"><span>Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)</span><br>
</blockquote>
<blockquote type="cite"><span>users mailing list users@lists.quantum-espresso.org</span><br>
</blockquote>
<blockquote type="cite"><span>https://lists.quantum-espresso.org/mailman/listinfo/users</span><br>
</blockquote>
<span></span><br>
<span></span><br>
<span>-- </span><br>
<span>Pietro Bonfà</span><br>
<span>Department of Mathematical, Physical and Computer Sciences,</span><br>
<span>University of Parma,</span><br>
<span>Italy</span><br>
<span>_______________________________________________</span><br>
<span>Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)</span><br>
<span>users mailing list users@lists.quantum-espresso.org</span><br>
<span>https://lists.quantum-espresso.org/mailman/listinfo/users</span></div>
</blockquote>
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