[Pw_forum] nspin=1 in NEB calculation

[Guido Fratesi]

Dear Jinghui,

>     I was wondering once i set nspin=1, do i have to settot_magnetization?

do you mean "nspin=2"? This is indeed the option for a spin-polarized 
(collinear) calculation, see Doc/INPUT_PW.txt

In that case, yes, you have to specify the starting magnetization of the 
system (there are a number of ways, again have a look to 
Doc/INPUT_PW.txt). And yes, the default is different from SIESTA where 
-forbid me, I'm not experienced of that code- imposing "spin_polarized 
true" implies by default a ferromagnetic starting point.

HTH,
Guido

  PS As for NEB, keep in mind that if the magnetization of your system is 
crucially depending on coordinates (as an example, if your transition 
state is magnetic but the initial and final states are not), then you 
might have some difficulty in imposing the true magnetized state for some 
image in the path, because the starting charge density might be 
extrapolated from previous steps where the system is not magnetic. In that 
case, you could either continue the calculation but restarting from atomic 
charges, or replace that charge from one of a separate, controlled SCF 
calculation.

-- 
Guido Fratesi

Dipartimento di Scienza dei Materiali
Universita` degli Studi di Milano-Bicocca
via Cozzi 53, 20125 Milano, Italy