Structure and interactions of ultracold Yb ions and Rb atoms

TL;DR

This paper investigates the potential energy surfaces and molecular interactions of ultracold Yb ions and Rb atoms using advanced quantum chemistry methods, providing insights into charge-transfer processes and scattering properties.

Contribution

It offers detailed ab initio calculations of molecular states and parameters for the Yb-Rb$^+$ system, including potential energy curves and scattering lengths, advancing understanding of ultracold atom-ion interactions.

Findings

Potential energy curves and molecular constants for Yb-Rb$^+$ states are computed.

Long-range interaction parameters, including dispersion coefficients, are estimated.

Adiabatic scattering lengths are large and negative, indicating strong interactions.

Abstract

In order to study ultracold charge-transfer processes in hybrid atom-ion traps, we have mapped out the potential energy curves and molecular parameters for several low lying states of the Rb, Yb$^+$ system. We employ both a multi-reference configuration interaction (MRCI) and a full configuration interaction (FCI) approach. Turning points, crossing points, potential minima and spectroscopic molecular constants are obtained for the lowest five molecular states. Long-range parameters, including the dispersion coefficients are estimated from our {\it ab initio} data. The separated-atom ionization potentials and atomic polarizability of the ytterbium atom ($\alpha_d=128.4$ atomic units) are in good agreement with experiment and previous calculations. We present some dynamical calculations for (adiabatic) scattering lengths for the two lowest (Yb,Rb$^+$) channels that were carried out in our work. However, we find that the pseudo potential approximation is rather limited in validity, and only applies to nK temperatures. The adiabatic scattering lengths for both the triplet and singlet channels indicate that both are large and negative in the FCI approximation.