  The structural features of the interface between the cystalline and amorphous
phases of Si solid are studied in simulations based on a combination of
empirical interatomic potentials and a nonorthogonal tight-binding model. The
tight-binding Hamiltonian was created and tested for the types of structures
and distortions anticipated to occur at this interface. The simulations
indicate the presence of a number of interesting features near the interface.
The features that may lead to crystallization upon heating include <110> chains
with some defects, most prominently dimers similar to those on the Si(001) 2x1
reconstructed free surface. Within the amorphous region order is lost over very
short distances. By examining six different samples with two interfaces each,
we find the energy of the amorphous-crystal interface to be 0.49 +/- 0.05 J/m^2
