Deviations from Born-Oppenheimer mass scaling in spectroscopy and ultracold molecular physics

Lutz, J.J.; Hutson, J.M.

doi:10.1016/j.jms.2016.08.007

Deviations from Born-Oppenheimer mass scaling in spectroscopy and ultracold molecular physics

Lutz, J.J.; Hutson, J.M.

Authors

J.J. Lutz

Professor Jeremy Hutson j.m.hutson@durham.ac.uk
Professor

Abstract

We investigate Born-Oppenheimer breakdown (BOB) effects (beyond the usual mass scaling) for the electronic ground states of a series of homonuclear and heteronuclear alkali-metal diatoms, together with the Sr2 and Yb2 diatomics. Several widely available electronic structure software packages are used to calculate the leading contributions to the total isotope shift for commonly occurring isotopologs of each species. Computed quantities include diagonal Born-Oppenheimer corrections (mass shifts) and isotopic field shifts. Mass shifts dominate for light nuclei up to and including K, but field shifts contribute significantly for Rb and Sr and are dominant for Yb. We compare the ab initio mass-shift functions for Li2, LiK and LiRb with spectroscopically derived ground-state BOB functions from the literature. We find good agreement in the values of the functions for LiK and LiRb at their equilibrium geometries, but significant disagreement with the shapes of the functions for all 3 systems.The differences may be due to contributions of nonadiabatic terms to the empirical BOB functions. We present a semiclassical model for the effect of BOB corrections on the binding energies of near-threshold states and the positions of zero-energy Feshbach resonances.

Citation

Lutz, J., & Hutson, J. (2016). Deviations from Born-Oppenheimer mass scaling in spectroscopy and ultracold molecular physics. Journal of Molecular Spectroscopy, 330, 43-56. https://doi.org/10.1016/j.jms.2016.08.007

Journal Article Type	Article
Acceptance Date	Aug 14, 2016
Online Publication Date	Aug 17, 2016
Publication Date	2016-12
Deposit Date	Aug 9, 2016
Publicly Available Date	Sep 7, 2016
Journal	Journal of Molecular Spectroscopy
Print ISSN	0022-2852
Publisher	Elsevier
Peer Reviewed	Peer Reviewed
Volume	330
Pages	43-56
DOI	https://doi.org/10.1016/j.jms.2016.08.007
Related Public URLs	https://arXiv.org/abs/1608.02141

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Copyright Statement
© 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://
creativecommons.org/licenses/by/4.0/).