Ab initio calculations of the electronic states of KRb Original Research Article

We have performed large-scale configuration interaction calculations for the electronic states of KRb dissociating into 4s+5s, 4s+5p, 4p+5s, 4s+4d, 4s+6s, 5s+5s, 3d+5s, 5s+6p and 5s+5d using the averaged relativistic effective core potentials. The core–valence correlation effect has been included through the use of the core-polarization potential. The core–core repulsion has been explicitly included by using small-core potential. Comparison with previous calculations without this term shows significant changes of the spectroscopic constants. The spin–orbit effect has been calculated by employing relativistic effective core potentials with spin–orbit operators. The most important changes caused by the spin–orbit interaction is the transformation of the 1 3Π and 2 1Σ+ states into five states characterized by the Ω quantum number. The 1 1Π state appears to be significantly perturbed by the 2 3Σ+ state through the spin–orbit coupling. The electric dipole moments and transition dipole moments for the excited states are also computed.