  Recent scanning tunneling microscopy on BSCCO 2212 has revealed a substantial
spatial supermodulation of the energy gap in the superconducting state. We
propose that this gap modulation is due to the superlattice modulations of the
atoms in the structure, and hence the parameters in a microscopic model of the
CuO2 plane. The gap modulation is estimated using renormalized mean field
theory for a t-t'-J model on a superlattice. The results compare well with
experiment.
