  Resonant scattering of optically state-prepared and aligned molecules in the
cold regime allows the most detailed interrogation and control of bimolecular
collisions. This technique has recently been applied to collisions of two
aligned ortho-D2 molecules prepared in the j=2 rotational level of the v=2
vibrational manifold using the Stark-induced adiabatic Raman passage technique.
Here, we develop the theoretical formalism for collisions of two aligned
molecules and apply our approach to state-prepared D2(v=2,j=2) + D2(v=2,j=2)
--> D2(v=2,j=2) + D2(v=2,j=0) collisions. Quantum scattering calculations were
performed in full-dimensionality on an accurate H$_2$-H$_2$ interaction
potential. Key features of the experimental angular distributions are
reproduced and attributed primarily to a partial wave resonance with orbital
angular momentum L=4
