Accurate calculation of the scattering length for the cooling of hydrogen atoms by lithium atoms

Ali improved ab initio calculation has been performed for the potential for the LiH a (3)Sigma (+) state, using two very large basis sets. The Basis S et Superposition Error (BSSE) correction has been determined for both basis sets and the non-Born-Oppenheimer correction estimated to be negligible. T he best potential is approximately 10% deeper than the previous estimate. V ibrational energies and scattering lengths have been calculated for (LiH)-L i-6.7(D) with both potentials. with and without the BSSE correction, and al so with an estimated potential expected to bracket the true potential. The (LiH)-Li-7 scattering length is estimated to be (45 +/- 4)a(0) and hence th e low-energy cross-section in the best a (3)Sigma (+) potential is about ha lf that calculated previously. Enhanced cooling by Li-7 of trapped H atoms remains feasible.