Atomic rubidium, the workhorse of theoretical collision physics

Since the first realizations of Bose-Einstein condensates in ultracold atomic gases in 1995, the 85Rb and 87Rb atomic species have acted as the workhorses of experimental developments in this field. Parallel to and partly preceding this work the same isotopes figured also as workhorses for successful theoretical attempts aiming at unravelling the needed information on interaction properties like scattering lengths and Feshbach resonances\footnote{Hugo Boesten, PhD thesis Eindhoven University (1996, ISBN 90-386-0019-4)}. The purpose of this contribution is to describe recent developments of this theoretical work, based on an adiabatic variant of the accumulated phase method, which gives rise to the most reliable and accurate predictions of interaction properties available to date for any alkali atomic gas\footnote {See preliminary description by E. van Kempen, S. Kokkelmans, D. Heinzen, and B. Verhaar, Phys. Rev. Lett. 88, 093201 (2002).}. The method can be readily applied to predict interaction properties between two different atomic species, once a limited set of experimental data is available to determine the accumulated phases.