Dear Sreekar, I would first try to reduce mixing_beta and also lambda (say, to 0.2 or 0.1). You can then restart the calculation with a larger value of lambda.
Don't forget that for USPP you need to specify also ecutrho, and perhaps you don't need such a high ecutwfc. If your USPPs are those on the QE website, I would use ecutwfc=35 and ecutrho=350, for instance. Il giorno 25/ago/2011, alle ore 12.25, sreekar guddeti ha scritto: > 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" Indeed this looks suspicious... one should look into the code to understand what's going on. You can have a look into add_bfield.f90, it should not be very difficult to understand how it works. Good luck GS > 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 > > <grapheneznrn10j.scf.in>_______________________________________________ > 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/20110825/ba3beab2/attachment-0001.htm
