Ultracold atom-dimer long-range interactions beyond the 1/Rn expansion
Abstract
We investigate theoretically the combination of first-order quadrupole-quadrupole and second-order dipole-dipole effects on the long-range electrostatic interactions between a ground-state homonuclear alkali-metal dimer and an excited alkali-metal atom. As the electrostatic energy is comparable to the dimer rotational structure, we develop a general description of the long-range interactions which allows for couplings between the dimer rotational levels. The resulting adiabatic potential energy curves, which exhibit avoided crossings, cannot be expanded on the usual 1/Rn series. We study in details the breakdown of this approximation in the particular case Cs2+Cs. Our results are found promising in the prospect of accomplishing the photoassociation of ultracold trimers.