<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt">Hi,<br><br>A couple of comments that might be useful.<br><br>1. As you use an US pseudopotential, reduce ecutwfc down to ~30Ry. I do not see any reason for such kind of high cutoff energy, unless you performed some tests and proved that 60Ry is better. Besides, for the same reason (US PsP), you should use more ecutrho (8-12 times of ecutwfc). By default ecutrho=4*ecutwfc (why so, think about) and this works for norm-conserving PsPs. <br><br>As a reference see N.Mounet and N. Marzari, Phys. Rev. B 71, 205214 (2005), where they used ecutoff=40Ry for graphene and other C-based structures.<br><br>2. I have noticed that the job started to converge when I used smaller efield_cart(3)=0.05, after 49 iteration I had<br><br> estimated scf
accuracy < 0.00007068 Ry<br><br>but then my notebook turned off due to a heating problem, I suggest. As I just tried to test the problem I used only 2x2x1 k-points set, and mixing_beta(1)=0.05. <br>But when I used efield_cart(3)=0.005 (with mixing coefficient 0.1) the job finished after 11 iterations. <br><div><br>Hope this helps.<br><br>Bests,<br>Eyvaz. <br>-------------------------------------------------------------------<br></div>Prof. Eyvaz Isaev, <br>Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden <br>Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, <br>isaev@ifm.liu.se, eyvaz_isaev@yahoo.com<div><br></div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr
size="1"><b><span style="font-weight: bold;">From:</span></b> Elie Moujaes <elie.moujaes@hotmail.co.uk><br><b><span style="font-weight: bold;">To:</span></b> pw_forum@pwscf.org<br><b><span style="font-weight: bold;">Sent:</span></b> Mon, December 13, 2010 1:57:36 PM<br><b><span style="font-weight: bold;">Subject:</span></b> [Pw_forum] Bilayer graphene subject to an electric field<br></font><br>
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<font size="3">Dear all,</font><br>
<font size="3"></font> <br>
<font size="3">I am trying to get the band structure of bilayer graphene under the effect of an external electric field. I have done the scf calculations without the inclusion of an electric field , then again did teh scf calculation with an electric field included in the z-direction (of value 0.1 Ry). However the convergence is not achieved and it stopped after 100 iterations giving the following message:</font><br>
<br>
<br>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>total cpu time spent up to now is<span style=""> </span>83435.11 secs<br><br><span style=""> </span>total energy<span style=""> </span>=<span style=""> </span>-52.83248336 Ry<br><span style=""> </span>Harris-Foulkes estimate<span style=""> </span>=<span style=""> </span>-45.80937450 Ry<br><span style=""> </span>estimated scf accuracy<span style=""> </span>< <span style=""> </span>0.00524127 Ry<br><br><span style=""> </span>End of self-consistent calculation<br><br><span
style=""> </span>convergence NOT achieved after 100 iterations: stopping</font><br></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"></span> </p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font style="font-size: 12pt;" face="Tahoma" size="3">You will find below the inout file for the scf calculation when an electric field is applied:</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font face="Tahoma" size="3"></font></span> </p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font face="Tahoma" size="3"></font></span> </p><span style="font-family: 'Courier New';" lang="EN-GB">
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>&control</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>prefix='bielgraphene',</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>calculation='scf',</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>restart_mode='from_scratch',</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>lelfield = .true.,</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font size="3"><span style="font-family: 'Courier New';" lang="EN-GB"><span style=""> </span></span><span style="font-family: 'Courier New';" lang="PT-BR">nberrycyc= 1,</span></font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="PT-BR"><font size="3"><span style=""> </span>pseudo_dir = '/espresso-4.2/pseudo/',</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font size="3"><span style="font-family: 'Courier New';" lang="PT-BR"><span style=""> </span></span><span style="font-family: 'Courier New';" lang="EN-GB">outdir='/tmp/results_MOUJAES/'</span></font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>/</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>&system<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>ibrav=<span style=""> </span>4, celldm(1) =4.608737, celldm(3)=5.330410, nat=4, ntyp= 1,</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>ecutwfc = 60.D0,occupations='smearing',smearing='methfessel-paxton', degauss=0.01</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3">/</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>&electrons</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>conv_thr=1.D-5,<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>mixing_mode='local-TF'</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>mixing_beta=0.1D0</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>efield_cart(1) = 0.000,</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>efield_cart(2) = 0.000,</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>efield_cart(3) = 0.10,</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>/</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3">ATOMIC_SPECIES</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>C<span style=""> </span>12.0107<span style=""> </span>C.pz-rrkjus.UPF</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3">ATOMIC_POSITIONS crystal</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>C 0.000000<span style=""> </span>0.000000<span style=""> </span>0.000000<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>C 0.000000<span style=""> </span>0.000000<span style=""> </span>0.257692 </font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>C 0.333333<span style=""> </span>-0.33333<span style=""> </span>0.000000<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>C -0.333333<span style=""> </span>0.33333<span style=""> </span>0.257692<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"> </font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3">K_POINTS automatic</font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><span style="font-family: 'Courier New';" lang="EN-GB"><font size="3"><span style=""> </span>25 25 1<span style=""> </span>0 0 0<span style=""> </span></font></span></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"> </p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"> </p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3">Thanks</font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3"></font> </p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3">Elie Moujaes</font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3">University of Nottingham</font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3">NG7 2RD</font></p>
<p class="MsoPlainText" style="margin: 0in 0in 0pt;"><font face="Tahoma" size="3">UK</font></p></span> <meta http-equiv="x-dns-prefetch-control" content="on"></div></div>
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