Ab initio calculation of the KRb dipole moments

TL;DR

This paper uses ab initio relativistic calculations to determine the electric dipole moments of KRb molecules and proposes a method to produce specific molecular states via a two-photon Raman process.

Contribution

It provides detailed calculations of KRb dipole moments and introduces a novel approach to synthesize singlet ground-state KRb molecules using relativistic effects.

Findings

Permanent dipole moment of ground state is 0.30(2) ea0.

Transition dipole moments enable a two-photon Raman process.

Relativistic spin-orbit coupling allows otherwise forbidden transitions.

Abstract

The relativistic configuration interaction valence bond method has been used to calculate permanent and transition electric dipole moments of the KRb heteronuclear molecule as a function of internuclear separation. The permanent dipole moment of the ground state $X^1\Sigma^+$ potential is found to be 0.30(2) $ea_0$ at the equilibrium internuclear separation with excess negative charge on the potassium atom. For the $a^3\Sigma^+$ potential the dipole moment is an order of magnitude smaller (1 $ea_0=8.47835 10^{-30}$ Cm) In addition, we calculate transition dipole moments between the two ground-state and excited-state potentials that dissociate to the K(4s)+Rb(5p) limits. Using this data we propose a way to produce singlet $X^1\Sigma^+$ KRb molecules by a two-photon Raman process starting from an ultracold mixture of doubly spin-polarized ground state K and Rb atoms. This Raman process is only allowed due to relativistic spin-orbit couplings and the absence of gerade/ungerade selection rules in heteronuclear dimers.