Dear Sreekar Guddeti, if you want to calculate a constrained magnetization with antiparallel direction between the atom 2 and atom 8, you must to put the "starting_magnetization" tag with opposite value, for example:
starting_magnetization(2)= 0.3091, starting_magnetization(8)= -0.3091, best wishes PhD stud. Arles V. Gil Rebaza Instituto de F?sica de La Plata Argentina. 2011/8/25 sreekar guddeti <colonel.sreekar at gmail.com> > 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 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- ###---------> Arles V. <---------### -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110825/01a1aa1e/attachment.htm
