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