  We consider one-dimensional solitons in a binary Bose-Einstein condensate
with linear coupling between the components, trapped in an optical-lattice
potential. The inter-species and intra-species interactions may be both
repulsive or attractive. Main effects considered here are spontaneous breaking
of the symmetry between components in symmetric and antisymmetric solitons, and
spatial splitting between the components. These effects are studied by means of
a variational approximation and numerical simulations.
