Higher-order Cn dispersion coefficients for the alkali-metal atoms

James Mitroy, Michael Bromley

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The van der Waals coefficients, from C11 through to C16 resulting from second-, third-, and fourth-order perturbation theory are estimated for the alkali-metal (Li, Na, K, and Rb) atoms. The dispersion coefficients are also computed for all possible combinations of the alkali-metal atoms and hydrogen. The parameters are determined from sum rules after diagonalizing a semiempirical fixed core Hamiltonian in a large basis. Comparisons of the radial dependence of the Cnrn potentials give guidance as to the radial regions in which the various higher-order terms can be neglected. It is seen that including terms up to C10r10 results in a dispersion interaction that is accurate to better than 1% whenever the inter-nuclear spacing is larger than 20a0. This level of accuracy is mainly achieved due to the fortuitous cancellation between the repulsive (C11,C13,C15) and attractive (C12,C14,C16) dispersion forces. � 2005 The American Physical Society.
    Original languageEnglish
    Pages (from-to)-
    JournalPhysical Review A - Atomic, Molecular, and Optical Physics
    Volume71
    Issue number4
    Publication statusPublished - 2005

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