Ultracold chemistry with alkali-metal-rare-earth molecules

12 págs.; 9 figs.; tab.; PACS number(s): 34.50.Cx, 34.50.Lf, 82.20.Xr© 2015 American Physical Society. A first principles study of the dynamics of Li6(2S)+Li6Yb174(2Σ+)→6Li2(1Σ+)+Yb174(1S) reaction is presented at cold and ultracold temperatures. The computations involve determination and analytic fitting of a three-dimensional potential energy surface for the Li2Yb system and quantum dynamics calculations of varying complexities, ranging from exact quantum dynamics within the close-coupling scheme, to statistical quantum treatment, and universal models. It is demonstrated that the two simplified methods yield zero-temperature limiting reaction rate coefficients in reasonable agreement with the full close-coupling calculations. The effect of the three-body term in the interaction potential is explored by comparing quantum dynamics results from a pairwise potential that neglects the three-body term to that derived from the full interaction potential. Inclusion of the three-body term in the close-coupling calculations was found to reduce the limiting rate coefficients by a factor of two. The reaction exoergicity populates vibrational levels as high as v=19 of the Li62 molecule in the limit of zero collision energy. Product vibrational distributions from the close-coupling calculations reveal sensitivity to inclusion of three-body forces in the interaction potential. Overall, the results indicate that a simplified model based on the long-range potential is able to yield reliable values of the total reaction rate coefficient in the ultracold limit but a more rigorous approach based on statistical quantum or quantum close-coupling methods is desirable when product rovibrational distribution is required.The Temple University and University of Nevada Las Vegas teams acknowledge support from the Army Research Office, MURI Grant No. W911NF-12-1-0476, and the National Science Foundation, Grants No. PHY-1308573 (S.K.) and No. PHY-1205838 (N.B.). T.G.L. acknowledges support from Project No. FIS2011-29596-C02-01 of the Spanish MICINN. B.K.K. acknowledges that part of this work was done under the auspices of the US Department of Energy under Project No. 20140309ER of the Laboratory Directed Research and Development Program at Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Los Alamos National Security, LLC, for the National Security Administration of the US Department of Energy under Contract No. DE-AC52-06NA25396.Peer Reviewe