Il giorno 11/mag/2011, alle ore 11.58, Gabriele Sclauzero ha scritto: > > How different are your optimized structural parameters from those reported in > the literature? > Looking at your input file, I would suggest to test convergence with degauss, > maybe 0.05 (Rydberg!) is too large.
Moreover smearing is not needed for diamond, since it has a large band gap, while graphene could also be converged without smearing or with a very small spread. > Also try shifted k-points meshes, they should give faster convergence. > > HTH > > GS > > > Il giorno 06/mag/2011, alle ore 11.20, Alexander G. Kvashnin ha scritto: > >> Dear PWSCF community >> >> In my study I got a problem which I can't solve by myself, >> unfortunately. I hope you can give me some tips where I made a >> mistake. I have to to investigate the energy difference between >> graphite and diamond, but I can't get trusted result.First of all, I >> used LDA PP (PZ), I tested it by subsequently increasing of energy >> cutoff (from 30 Ry to 120 Ry) as well as increasing of k-points mesh >> (4x4x1 for graphite, 4x4x4 for diamond; 6x6x2 for graphite, 6x6x6 for >> diamond; >> 8x8x3 for graphite, 8x8x8 for diamond; 10x10x4 for graphite, 10x10x10 for >> diamond). >> I got the difference between energies of diamond and graphite and tried to >> understand it >> trend (please, see attached figure). As you can see from the figure >> difference between energy diamond and graphite is almost zero so I >> can't say with confidence what structure is more favorable. >> This result different from other theoretical and experimental >> studies, therefore it seems that I did something wrong... >> >> My result: ~ 0.001?0.001 eV/atom >> >> _______________________________________________ >> >> | Energy difference (eV/atom) | Method | Reference | >> | 0.03 |Experiment | PRB29_6996 | >> | 0.01 | LDA-PP | PRB29_6996 | >> | 0.04 | LDA-PP | PRB54_14994| >> >> ----------------------------------------------------------------------------------- >> >> Input files for diamond and graphite are attached to the letter. >> >> >> -- >> Sincerely yours >> Alexander G. Kvashnin >> -------------------------------------------------------------------------------------------------------------------------------- >> First year of master degree study >> Moscow Institute of Physics and Technology http://mipt.ru/ >> 141700, Institutsky lane 9, Dolgoprudny, Moscow Region, Russia >> >> Junior research scientist >> Technological Institute for Superhard >> and Novel Carbon Materials >> http://www.ntcstm.troitsk.ru/ >> 142190, Central'naya St. 7a, Troitsk, Moscow Region, Russia >> ================================================================ >> >> <input_diamond.opt><input_graphite.opt><Energy_difference.GIF>_______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum > > > ? Gabriele Sclauzero, EPFL SB ITP CSEA > PH H2 462, Station 3, CH-1015 Lausanne > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum ? Gabriele Sclauzero, EPFL SB ITP CSEA PH H2 462, Station 3, CH-1015 Lausanne -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110511/ce68efb1/attachment-0001.htm
