The First Principle Analysis of Spin-Orbit Interaction between Excited Electronic States of the KRb Molecule

Within the scalar-relativistic and full relativistic approximation, ab initio calculations of the electronic structure for all singlet and triplet states of the KRb molecule converging to the first two excited dissociation thresholds were performed. The adiabatic interatomic potentials and spin-orbit electronic matrix elements derived within of the framework of “a” and “c” Hund’s coupling case as a function of the inter-nuclear distance have allowed the asymmetry puzzle of the fine structure Ω = 0 +/– , 1, 2-splitting experimentally observed for vibrational levels of the triplet d 3 Π Ω state of KRb.