Ab initio interaction potentials and scattering lengths for ultracold mixtures of metastable helium and alkali-metal atoms

We have obtained accurate ab initio (4)Sigma(+) quartet potentials for the diatomic metastable triplet helium+ alkalimetal (Li, Na, K, Rb) systems, using all-electron restricted open-shell coupled cluster singles and doubles with noniterative triples corrections CCSD(T) calculations and accurate calculations of the long-range C-6 coefficients. These potentials provide accurate ab initio quartet scattering lengths, which for these many-electron systems is possible, because of the small reduced masses and shallow potentials that result in a small amount of bound states. Our results are relevant for ultracold metastable triplet helium+ alkali-metal mixture experiments.