  We analyze the quantum states of two atoms in a combined harmonic oscillator
and periodic lattice trap in one spatial dimension. In the case of
tight-binding and only nearest neighbor tunneling, the equations of motion are
conveniently represented in the momentum representation. We show that in the
case of strong attraction between the particles, the different time scales of
relative and center-of-mass motion validate a separation of the problem similar
to the Born-Oppenheimer approximation applied in the description of electronic
and nuclear motion in molecules.
