ChaNGa (Charm N-body GrAvity solver) performs collisionless N-body simulations. It can perform cosmological simulations with periodic boundary conditions in comoving coordinates or simulations of isolated stellar systems. It also can include hydrodynamics using the Smooth Particle Hydrodynamics (SPH) technique. It uses a Barnes-Hut tree to calculate gravity, with hexadecapole expansion of nodes and Ewald summation for periodic forces. Timestepping is done with a leapfrog integrator with individual timesteps for each particle.
Please cite http://www.computer.org/csdl/proceedings/ipdps/2008/1693/00/04536319-abs.html, http://www.computer.org/csdl/proceedings/sc/2010/7559/00/75590046-abs.html, and http://adsabs.harvard.edu/abs/2015ComAC...2....1M