[SIESTA-L] Using FixSpin and TotalSpin to force anti-ferromagnetic state

[Toma Susi]

Hello,

I am trying to calculate the difference of ferromagnetic and 
anti-ferromagnetic states of magnetic adatoms on a carbon system. 
Ferromagnetic is no problem, SpinPolarized TRUE takes care of that. But 
for the anti-ferromagnetic state, even with DM.InitSpinAF TRUE the spins 
seem to always flip to a ferromagnetic order.

So I thought that taking the above as TRUE and also setting FixSpin TRUE 
and TotalSpin 0.0 would do the trick. As it seems to do, but the 
question is: is this physical? Does this correspond to the same system 
with the only difference being the anti-ferromagnetic order? Or does 
fixing the spin like this force some effects, maybe affecting the energy?

Thanks very much for any thoughts on the issue,

Toma Susi
Helsinki University of Technology