Ab initio calculation of the KRb dipole moments.pdf

a r X i v : c o n d - m a t / 0 3 0 5 2 1 5 v 1 [ c o n d - m a t .s o f t ] 9 M a y 2 0 0 3 Ab initio calculation of the KRb dipole moments S. Kotochigova, P. S. Julienne, and E. Tiesinga National Institute of Standards and Technology, 100 Bureau Drive, stop 8423, Gaithersburg, Maryland 20899. Abstract The relativistic configuration interaction valence bond method has been used to calculate permanent and transition electric dipole moments of the KRb het- eronuclear molecule as a function of internuclear separation. The permanent dipole moment of the ground state X1Σ+ potential is found to be 0.30(2) ea0 at the equilibrium internuclear separation with excess negative charge on the potassium atom. For the a3Σ+ potential the dipole moment is an order of magnitude smaller (1 ea0 = 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 X1Σ+ 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. PACS numbers: 03.75.Fi, 03.75.Be, 03.75.-b Typeset using REVTEX 1 In heteronuclear diatomic molecules the electrons can be distributed between the two nuclei unequally. As a result, there can be a small excess of negative charge near the more electronegative atom and thus heteronuclear dimers can have a permanent dipole moment. In this study we calculate the permanent dipole moments of the 1,3Σ+ electronic states of the KRb ground configuration, which dissociate to the K(4s)+Rb(5s) limit, and transition dipole moments between these states and excited states, which dissociate to K(4s)+Rb(5p) limits. Simple analysis of the ionization energies of K and Rb atoms, 4.339 eV and 4.176 e