An ab initio study of the ground and low-lying excited states of KBe with the effect of inner-shell electrons

The potential energy curves (PECs) of 1²Σ⁺, 2²Σ⁺, 1²Π, and 2²Π states of KBe are calculated using multireference configuration interaction method and large all-electron basis sets. Four sets of frozen core orbitals (FCOs) are considered to examine the effect of inner-shell correlation electrons on the molecular properties. The ro-vibrational energy levels are obtained by solving the Schrödinger equation of nuclear motion based on the ab initio PECs. The spectroscopic parameters are determined from the ro-vibrational levels with Dunham expansion. The PECs are fitted into analytical potential energy functions using the Morse long-range potential function. The dipole moment functions of the states for KBe calculated with different FCOs are presented. The transition dipole moments for KBe between 1²Σ⁺ and 2²Σ⁺ states, 1²Π and 1²Σ⁺ states, and 2²Π and 1²Σ⁺ states are also obtained.