Eliseo, The numbers you are showing for the spins are extracted from some integration over the densities, or those are the mulliken charges on the system? I will suppose that those are the numbers that come out after one or more complete self-consistency cycles; if it is so, it means that your system "doesn't want to keep" the initial values you have supplied; it will be more advantageous, energetically, to have the final configuration of spins. The initial configuration is just a starting guess, but self-consistency takes over after this. Nothing guarantees that you will have the final global net spin, or the individual net spins of the atoms, equal to the initial values after a whole SCF cycle. Actually, you can constrain the total magnetization of a system in siesta, but I am not sure if the total magnetization would be constrained over all the scf steps.
Cheers, Marcos Vous avez écrit / You have written / Lei ha scritto / Você escreveu... Eliseo Ruiz > Dear Colleagues, > > I am calculating a periodic system with 40 Cu(II) cations in the > unit cell. I am trying to > calculate the energy for the different spin distributions. However, > only in a couple of > cases I obtain the signs of the spins that I specified in the input > file. For instance, for one > of the spin distributions: > > ............ > # Spin defintion > SpinPolarized T > FixSpin T > TotalSpin 8.0 > %block DM.InitSpin > 1 +1.0 > 2 -1.0 > 3 -1.0 > 4 +1.0 > 5 +1.0 > 6 +1.0 > 7 -1.0 > 8 -1.0 > 9 +1.0 > 10 +1.0 > 11 +1.0 > ............ > 40 +1.0 > %endblock DM.InitSpin > > the results for the spin density: > atom up down total > 1 4.968 -5.401 -.433 > 2 4.978 -5.411 -.433 > 3 5.397 -4.948 .449 > 4 5.406 -4.942 .464 > 5 5.431 -4.963 .468 > 6 5.407 -4.962 .445 > 7 5.415 -4.977 .438 > 8 4.957 -5.391 -.434 > 9 4.943 -5.404 -.461 > 10 5.439 -4.964 .475 > 12 5.420 -4.987 .433 > ............ > > The total spin is satisfied but not the local spins. I tried several > options of DM.MixingWeight and > DM.NumberPulay as well as for ElectronicTemperature but I cannot > reach the selected spin > distribution. > > best wishes, > > Eliseo > -- Dr. Marcos Verissimo Alves Post-Doctoral Fellow Unité de Physico-Chimie et de Physique des Matériaux (PCPM) Université Catholique de Louvain 1 Place Croix du Sud, B-1348 Louvain-la-Neuve Belgique ------ Gort, Klaatu barada nikto. Klaatu barada nikto. Klaatu barada nikto.
