  We present a new open-source software package, FIT-MART, that allows
non-experts to quickly get started simulating quantum magnetism. FIT-MART can
be downloaded as a platform-idependent executable Java (JAR) file. It allows
the user to define (Heisenberg) Hamiltonians by electronically drawing pictures
that represent quantum spins and operators. Sliders are automatically generated
to control the values of the parameters in the model, and when the values
change, several plots are updated in real time to display both the resulting
energy spectra and the equilibruim magnetic properties. Several experimental
data sets for real magnetic molecules are included in FIT-MART to allow easy
comparison between simulated and experimental data, and FIT-MART users can also
import their own data for analysis and compare the goodness of fit for
different models.
