We extend recent work on two closely spaced atoms interacting through
the narrow band of strongly coupled modes at the edge of a photonic ba
nd gap. The resonant dipole-dipole interaction (RDDI) is strongly modi
fied for atomic transition frequencies in the vicinity of the band-gap
edge, but we show that an analytical approximation to the RDDI agrees
very well with the exact RDDI obtained by numerical integration using
the exact dispersion relation. Having established the value of the RD
DI, we can derive the amplitudes for the two atoms without resorting t
o the pole approximation which is necessary due to the strongly modifi
ed mode structure in the dielectric host. For a wide range of paramete
rs we find beating and population trapping in the long time limit. The
distribution of population in the photonic continuum is investigated
in the long time limit in the case of one and two atoms. It is found t
o be strongly asymmetric and to exhibit a strong signature of the unus
ual mode structure in the material at the band-gap edge.