  Mergoassociation of two ultracold atoms to form a weakly bound molecule can
occur when two optical traps that each contain a single atom are merged.
Molecule formation occurs at an avoided crossing between a molecular state and
the lowest motional state of the atom pair. We develop the theory of
mergoassociation for pairs of nonidentical nonspherical traps. We develop a
coupled-channel approach for the relative motion of the two atoms and present
results for pairs of cylindrically symmetrical traps as a function of their
anisotropy. We focus on the strength of the avoided crossing responsible for
mergoassociation. We also develop an approximate method that gives insight into
the dependence of the crossing strength on aspect ratio.
