  A grain boundary which separates domains with different orientation along the
c-axis is analyzed. The coupling of two parallel superconducting planes whose
order parameters are rotated leads to interesting properties which are expected
to be common to other kinds of grain boundary. The density of states is
enhanced at low energies. The number of localized states depends on the degree
of misfit across the boundary. A continuum of zero energy states appears at
certain values of the angle rotation.
