  We develop and validate a computational approach to nanomagnets. It is built
on the spin wave approximation to a Heisenberg ferromagnet whose parameters can
be calculated from a first principles theory (e.g. density functional theory).
The method can be used for high throughput analysis of a variety of
nanomagnetic materials. We compute the dependence of the magnetization of an
iron nanomagnet on temperature, size and shape. The approach is applied to
nanomagnets in the range of 432 atoms to 59 million atoms, a size which is
several orders of magnitude beyond the scalability of density functional
theory.
