Questions on constraints

[Jacob Gayles]

In there any documentation on how the constraints work?

i.e. what is the difference between hybrid constraint and regular constraint.

e.g. If I wanted to look at a 2D triangular lattice for the FM case the minimum energy would be out of the plane. However in the AFM in case the spins would be 120-rotated in the plane, is this the proper time to use constraints?

Regards,

Jacob

[Jacob Gayles]

Also is there anyway to constrain the total magnetic moment?

[richard....@gmail.com]

Hi Jacob,

The regular constraint constrains a single material, the hybrid constraint can optionally constrain multiple materials or do normal Monte Carlo for different materials in the same simulation. Typically for AFMs the hybrid constraint is probably best since constraining a single sublattice should be sufficient to calculate the energy surface, though this would be a fairly advanced use of the code. I admit the documentation for this feature is virtually non-existent, but mainly because it is a complex procedure and I haven't had time to write it up yet. I am not sure when this will be available, but if you have some specific questions I can probably help with those.

Regarding the last point, the current algorithm only constrains the direction, not magnitude of the magnetisation.

All the best,

Richard

[Jacob Gayles]

Thanks very much for the quick reply. I think I found my problem...

In the Monte Carlo run there is a process for the equilibration temperature, and the default is at 300 K. correct?  However if the Tc of the system is below 300 K one would need more loop steps in the system? correct?

Also If I wanted to calculate the heat capacity i.e. ~<E^2> -<E>^2 is this already a function for this, or due I take this from the loop series myself with these two commands (output:total-energy output:mean-total-energy)

Regards,

Jacob