  We propose a new method for generating equilibrium models of spherical
systems of collisionless particles that are finite in extent, but whose central
regions resemble dark matter halos from cosmological simulations. This method
involves iteratively removing unbound particles from a Navarro-Frenk-White
profile truncated sharply at some radius. The resulting models are extremely
stable, and thus provide a good starting point for N-body simulations of
isolated halos. We provide a code to generate such models for NFW and a variety
of other common density profiles. We then develop an analytic approximation to
this truncated distribution function. Our method proceeds by analogy with the
King model, truncating and shifting the original distribution function of an
infinitely extended Navarro-Frenk-White profile in energy space. We show that
the density profiles of our models closely resemble the tidally truncated
density profiles seen previously in studies of satellite evolution. Pursuing
this analogy further with a series of simulations of tidal mass loss, we find
that our models provide a good approximation to the full distribution function
of tidally stripped systems, thus allowing theoretically motivated phase-space
calculations for such systems.
