  We present a study of the existence, stability and bifurcation structure of
families of dark breathers in a one-dimensional uniform chain of spherical
beads under static load. A defocus- ing nonlinear Schrodinger equation (NLS) is
derived for frequencies that are close to the edge of the phonon band and is
used to construct targeted initial conditions for numerical computations.
Salient features of the system include the existence of large amplitude
solutions that bifurcate with the small amplitude solutions described by the
NLS equation, and the presence of a nonlinear instability that, to the best of
the authors knowledge, has not been observed in classical Fermi- Pasta-Ulam
lattices. Finally, it is also demonstrated that these dark breathers can be
detected in a physically realistic way by merely actuating the ends of an
initially at rest chain of beads and inducing destructive interference between
their signals.
