Hi Paolo,
>>* the restriction is in this code *>>* if ( ((MOD(NINT(tot_magnetization_),2) == 0) .and. (MOD *>>* (NINT(nelec_),2)==1)) .or. & *>>* ((MOD(NINT(tot_magnetization_),2) == 1) .and. (MOD *>>* (NINT(nelec_),2)==0)) ) & *>>* CALL errore(' set_nelup_neldw *>>* ', & *>>* 'tot_magnetization is inconsistent with total number *>>* of electrons ', 2 ) * >in the new version, this restriction (now a warning, no longer an >error) applies only if the >number of electrons is integer and if the magnetization is integer. >For noninteger charge >or magnetization, it doesn't make sense. In fact, increasing the k-point sampling, the unrestricted calculation converges towards 0 total magnetization, with a lower energy than magnetization =1, but setting tot_magnetization=0, or 0.1, 0.2, etc, stops due to the above instruction in versiom 4.2.1. This is one more reason to change to the newest version. *You stated something in a previous post* <pw_forum%40pwscf.org?Subject=%5BPw_forum%5D%20why%20are%20there%20two%20Fermi%20energies%3F&In-Reply-To=0CD095EE-2EC8-4E33-9F7F-334812E8089C%40sissa.it> >The "two Fermi energies" of the constrained >case need not to be exactly the same as the (single) >Fermi energy of the unconstrained case, as long as the >occupancies for spin-up and spin-down are the same in the >two cases. Why not? Aren't the the energies and occupations related by the Fermi-Dirac function? I verified that the occupations are the same, then I do not understand why it is possible with different Fermi energies. These are my KS energies and the occupations, using degauss=0.00019. I think the differences are just numerical noise. 1) tot_magnetization unset the Fermi energy is 6.1614 ev ! total energy = -502.92571441 Ry total magnetization = 1.00 Bohr mag/cell up: 4.8593 4.8594 5.2221 5.2221 5.2222 6.1335 6.1336 6.1338 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 dw: 4.8796 4.8796 5.2528 5.2530 5.2531 6.1595 6.1596 6.1596 1.0000 1.0000 1.0000 1.0000 1.0000 0.6709 0.6661 0.6631 2) tot_magnetization=1 the spin up/dw Fermi energies are 6.3853 6.1614 ev ! total energy = -502.92571439 Ry total magnetization = 1.00 Bohr mag/cell up: 4.8593 4.8594 5.2221 5.2221 5.2221 6.1335 6.1337 6.1338 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 dw: 4.8796 4.8796 5.2528 5.2530 5.2531 6.1595 6.1596 6.1596 1.0000 1.0000 1.0000 1.0000 1.0000 0.6715 0.6660 0.6625 Finally, I plotted Energy vs magnetization. Indeed, I have a minimum at total magnetization equal 1. However, the behavior is strange. The plot of E vs M is linear at each side of the minimum, with a kink at M=1. Should'n it be rather like a parable ? Please, see the plots here http://www.gnm.cl/emenendez/pmwiki.php/Temp/Plots?action=upload&upname=impurity-energy.eps http://www.gnm.cl/emenendez/pmwiki.php/Temp/Plots?action=upload&upname=impurity-fermi.eps This was using gamma point fo sample the Brillouin zone. That is not converged, using a 3x3x3 grid the lowest energy seems to be for null magnetization (I am doing more calculations). Maybe the kinks are due to insufficient Brillouin zone sampling. Best regards -- Eduardo Menendez Departamento de Fisica Facultad de Ciencias Universidad de Chile Phone: (56)(2)9787439 URL: http://fisica.ciencias.uchile.cl/~emenendez -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110425/1241523a/attachment-0001.htm