Respected Sir/Madam, 1. I would like to perform a constrained magnetization calculation for a system, whose unconstrained spin polarized calculation gives an antiferromagnetic state, to converge at the ferromagnetic state. 2. The system is a zigzag graphene nanoribbon(* http://en.wikipedia.org/wiki/Graphene***) and I would like to flip the atomic moment at one of the edge site and constrain both the edge site moments. 3. I calculated the antiferromagnetic edge site moment using PDOS calculation. I used 'lambda' parameter to constrain the moments.
4.Questions: Is 3) the right way to do it? If yes, what should be value of lambda? I used lambda =1 and the scf output (given below) is disturbing... I would like to ask what does "constrained moment : -20.000000" mean and why is the constrain energy so high. If it is not the right way, I would be grateful if you could suggest an alternative. Thanking you, Yours sincerely, Sreekar Guddeti Undergraduate (5th year) Engineering Physics IIT Bombay India PS: The system namelist for scf calculation and the sample output are given below and the complete input file is attached. -------------------------------------- ... ============================================================================== atom number 15 relative position : -3.5000 6.0622 0.0000 charge : 0.983302 magnetization : 0.000256 magnetization/charge: 0.000260 constrained moment : 0.309100 ============================================================================== ============================================================================== atom number 16 relative position : -3.0000 5.7735 0.0000 charge : 1.783674 magnetization : -0.385046 magnetization/charge: -0.215873 constrained moment : -20.000000 ============================================================================== ... ... *constraint energy* (Ryd) = 6095.83663339 --------------------------------- -------------------------------- &SYSTEM ibrav = 12, celldm(1) = 4.608737, celldm(2) = 12.0, celldm(3) = 10.0, celldm(4) = -0.50, nat = 18, ntyp =10, starting_magnetization(2)= 0.3091, starting_magnetization(8)= 0.3091, occupations='smearing', smearing='gauss', degauss=0.01, nspin=2, constrained_magnetization='atomic' lambda = 1 ecutwfc = 50.D0 , report = 2 / -- Sreekar Guddeti -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110825/c5288b4a/attachment.htm -------------- next part -------------- A non-text attachment was scrubbed... Name: grapheneznrn10j.scf.in Type: application/octet-stream Size: 2522 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110825/c5288b4a/attachment.obj