Effect of nuclear spin symmetry in cold and ultracold reactions: D plus para/ortho-H2

We report results for reaction and vibrational quenching of the collision D with para-H-2(v, j = 0) and ortho-H-2(v, j = 1) at cold and ultracold temperatures. We investigate the effect of nuclear spin symmetry for barrier dominated processes (0 <= v <= 4) and for one barrierless case (v = 5). We find resonant structures for energies in the range corresponding to 0.01-10 K, which depend on the nuclear spin of H-2, arising from contributions of specific partial waves. We discuss the implications on the results in this benchmark system for ultracold chemistry.