Dear Prof. Eyvaz, Thanks a lot for the information. Everything is solved now.. Elie
Date: Tue, 14 Dec 2010 13:40:59 -0800 From: [email protected] To: pw_forum at pwscf.org Subject: Re: [Pw_forum] Bilayer graphene subject to an electric field Hi, A couple of comments that might be useful. 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. 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. 2. I have noticed that the job started to converge when I used smaller efield_cart(3)=0.05, after 49 iteration I had estimated scf accuracy < 0.00007068 Ry 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. But when I used efield_cart(3)=0.005 (with mixing coefficient 0.1) the job finished after 11 iterations. Hope this helps. Bests, Eyvaz. ------------------------------------------------------------------- Prof. Eyvaz Isaev, Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com From: Elie Moujaes <[email protected]> To: pw_forum at pwscf.org Sent: Mon, December 13, 2010 1:57:36 PM Subject: [Pw_forum] Bilayer graphene subject to an electric field Dear all, 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: total cpu time spent up to now is 83435.11 secs total energy = -52.83248336 Ry Harris-Foulkes estimate = -45.80937450 Ry estimated scf accuracy < 0.00524127 Ry End of self-consistent calculation convergence NOT achieved after 100 iterations: stopping You will find below the inout file for the scf calculation when an electric field is applied: &control prefix='bielgraphene', calculation='scf', restart_mode='from_scratch', lelfield = .true., nberrycyc= 1, pseudo_dir = '/espresso-4.2/pseudo/', outdir='/tmp/results_MOUJAES/' / &system ibrav= 4, celldm(1) =4.608737, celldm(3)=5.330410, nat=4, ntyp= 1, ecutwfc = 60.D0,occupations='smearing',smearing='methfessel-paxton', degauss=0.01 / &electrons conv_thr=1.D-5, mixing_mode='local-TF' mixing_beta=0.1D0 efield_cart(1) = 0.000, efield_cart(2) = 0.000, efield_cart(3) = 0.10, / ATOMIC_SPECIES C 12.0107 C.pz-rrkjus.UPF ATOMIC_POSITIONS crystal C 0.000000 0.000000 0.000000 C 0.000000 0.000000 0.257692 C 0.333333 -0.33333 0.000000 C -0.333333 0.33333 0.257692 K_POINTS automatic 25 25 1 0 0 0 Thanks Elie Moujaes University of Nottingham NG7 2RD UK _______________________________________________ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20101217/733d6536/attachment-0001.htm
