Characterizing quasibound states and scattering resonances

Abstract

Characterizing quasibound states from coupled-channel scattering calculations can be a laborious task, involving extensive manual iteration and fitting. We present an automated procedure, based on the phase shift or S-matrix eigenphase sum, that reliably converges on a quasibound state (or scattering resonance) from some distance away. It may be used for both single-channel and multichannel scattering. It produces the energy and width of the state and the phase shift of the background scattering, and hence the lifetime of the state. It also allows extraction of partial widths for decay to individual open channels. We demonstrate the method on a very narrow state in the Van der Waals complex Ar--H${}_2$, which decays only by vibrational predissociation, and on near-threshold states of ${}^{85}$Rb${}_2$, whose lifetime varies over 4 orders of magnitude as a function of magnetic field.

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Cited by in corpus (9)

• Observation of Efimov Universality across a Non-Universal Feshbach Resonance in \textsuperscript{39}K
• Probing open- and closed-channel p-wave resonances
• Ab initio calculation of the spectrum of Feshbach resonances in NaLi + Na collisions
• Controlling collisional loss and scattering lengths of ultracold dipolar molecules with static electric fields
• Prospects of forming high-spin polar molecules from ultracold atoms
• Feshbach resonances and molecule formation in ultracold mixtures of Rb and Yb(${}^3$P) atoms
• Spin--spin interaction and magnetic Feshbach resonances in collisions of high-spin atoms with closed-shell atoms
• User Manual for MOLSCAT, BOUND and FIELD, Version 2025.0: programs for quantum scattering properties and bound states of interacting pairs of atoms and molecules
• Characterization of Feshbach resonances in ${}^6\mathrm{Li}{-}^7\mathrm{Li}$ using improved interaction potentials