fmag

Alloy Theoretic Automated Toolkit (ATAT)
1

Hi,

Is there any documentation on fmag? Is this MCE? I would like to calculate the spin entropy of some alloys as a function of temperature. Can fmag be used for this?

Thanks

2

This (very simple!) code gives the textbook mean field approximation for a system of quantum spins with nearest neighbor interactions. You just need to figure out the "coupling constant" (-cc input parameter) from two calculations: one ferromag and one antiferromag ordering. You can get the -sp parameter (spin value) from the mag moment in the ferromag calc, rounded to the nearest half integer. Type "fmag" alone for all the input param.
Warning: this is very approximate!

See also the fempmag code for a semi-empirical model described in I. Ohnuma et al., Phase equilibria in the Fe-Co binary system, Acta Materialia 50 (2002) 379.
Also approximate.

Spins are difficult to handle rigosrously, there were many recent PRLs on just doing this right for pure Ni or Fe!