### Abstract

We calculate near-threshold bound states and Feshbach resonance positions for atom–rigid-rotor models of the highly anisotropic systems Li+CaH and Li+CaF. We perform statistical analysis on the resonance positions to compare with the predictions of random matrix theory. For Li+CaH with total angular momentum J=0 we find fully chaotic behavior in both the nearest-neighbor spacing distribution and the level number variance. However, for J>0 we find different behavior due to the presence of a nearly conserved quantum number. Li+CaF (J=0) also shows apparently reduced levels of chaotic behavior despite its stronger effective coupling. This may indicate the development of another good quantum number relating to a bending motion of the complex. However, continuously varying the rotational constant over a wide range shows unexpected structure in the degree of chaotic behavior, including a dramatic reduction around the rotational constant of CaF. This demonstrates the complexity of the relationship between coupling and chaotic behavior.

Original language | English |
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Article number | 052713 |

Number of pages | 11 |

Journal | Physical Review A (Atomic, Molecular, and Optical Physics) |

Volume | 93 |

Issue number | 5 |

DOIs | |

Publication status | Published - 23 May 2016 |

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## Cite this

Frye, M. D., Morita, M., Vaillant, C. L., Green, D. G., & Hutson, J. M. (2016). Approach to chaos in ultracold atomic and molecular physics: Statistics of near-threshold bound states for Li+CaH and Li+CaF.

*Physical Review A (Atomic, Molecular, and Optical Physics)*,*93*(5), [052713]. https://doi.org/10.1103/PhysRevA.93.052713