---------- Forwarded message ---------- From: meysam pazoki <[email protected]> Date: Tue, Aug 17, 2010 at 3:54 PM Subject: Graphene Structural Relaxation To: pw_forum at pwscf.org
---------- Forwarded message ---------- From: meysam pazoki <[email protected]> Date: Tue, Jul 20, 2010 at 11:46 PM Subject: Graphene Structural Relaxation To: pw_forum-request at pwscf.org Dear PWSCF users I have a problem in relaxation of grahene super cell with 24 atoms. In relaxation procedure ,graphene hooney-comb structure completely destroys and atoms have no regular ordering after relaxation procedure.I use pbe-rrkjus psudopotential,4 3 3 kpoint grid,30 rydberg cutff energy,300 rydberg ecutrho. I use both ion_damps & bfgs algorithms and get similar results. If i change the ecutrho to 100, atoms have an irregular positions in 3 dimension,but when ecut rho set to 300 atoms have irregular position in-plane. furthermore if i set :trust_radius_ini=.1D0,trust_radius_max=.3D0,bfgs_ndim = 3, I have the honeycomb structure but some of c atoms exprience great forces like: atom 19 type 1 force = 11948.08469282 -219.69802882 0.00000000 atom 20 type 1 force = 11782.00343549 12.01959200 0.00000000 atom 21 type 1 force = 11748.09287051 115.25218004 0.00000000 atom 22 type 1 force = 11241.09464255 -222.56999757 0.00000000 atom 23 type 1 force = -0.50941109 0.26861287 0.00000000 atom 24 type 1 force = 11905.77649683 -91.34763119 0.00000000 My question is what is wrong in my structure relaxation procedure that result in such non-physical data. It would appreciated if anyone can help me in this problem Thanks in advance meysam pazoki Ph.D student of physics Sharif university of technology -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100817/84d24500/attachment.htm
