Spectroscopic constants and potential energy curves for 18 electronic states of IrH +

Abstract

Spectroscopic constants and potential energy curves of 18 electronic states of IrH + are obtained using the complete active space multi-configuration self-consistent field (CASMCSCF) followed by first-order configuration interaction (FOCI) and multi-reference singles + doubles CI (MRSDCI) calculations. The spin-orbit effects are introduced using the relativistic-configuration-interaction (RCI) method. The ground state of IrH + is found to be of 4Σ − symmetry with r e = 1.548 A ̊ , ω e = 2296 cm −1, and D e = 3.28 eV in the absence of spin-orbit interactions, while three nearly degenerate states [ 1 2 ( I) , 1 2 ( II) , 9 2 ( I) ] are found as candidates for the ground state including spin-orbit coupling. Several optical transitions for IrH + are predicted, none of which has been observed experimentally. The nature and bonding of the low-lying electronic states are analyzed.