[Octopus-users] Local magnetic moments

[Micael Oliveira]

Hi,

  Yes, the units are in bohr magnetons, but that's not the problem. The 
local magnetic moments in Octopus are compute by integrating the 
magnetization density in a sphere around each atom. This means the sum 
of those values will usually not give the total magnetic moment.
  Also, the default value for the radius of the spheres is the biggest 
one for which the individual sphere do not overlap. Maybe if you 
increase the radius you will get local magnetic moments closer to the 
ones you were expecting.
  In any case, the local magnetic moments as they are outputted by 
Octopus should only be used in a qualitative way: they will just give 
you an idea of how big they are where they are pointing to, so that one 
can distinguish ferromagnetic, anti-ferromagnetic and paramagnetic 
configurations.

  Cheers,

Micael

fampl at usc.es wrote:
> Dear Octopus-users,
> 
> I have been performing some computations in small silver cluster with
> octopus2.0.1. However, I'm mystified wiht the values of the local magnetic
> moment calculated by octopus for Ag3. They are:
> 
> Total Magnetic Moment:
>  mz =   1.000000
> Local Magnetic Moments (sphere radius [A] =   1.302):
>  Ion                    mz
>    1        Ag       0.177066
>    2        Ag      -0.006602
>    3        Ag       0.177135
> 
> The total magnetic moment is 1 bohr magneton and it is right but the local
> magnetic moment of Ag1 and Ag3 atoms should be close to 0.5 bohr magnetons
> whereas the local magnetic moment of Ag2 is close to 0. Are the units of the
> local mangetic moment reported by octopus in bohr magnetons? or maybe it should
> be multiplied by a predefined factor.
> 
> 
> Best Regards,
> Manuel.
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