Spectroscopic properties and potential energy surfaces of In2

Abstract

Complete active space MCSCF (CASSCF) followed by first-order configuration interaction (FOCI) and relativistic configuration interaction (RCI) calculations are carried out on 29 electronic states of In2. Spectroscopic properties of 19 electronic states below 34 000 cm−1 are calculated. The ground state of In2 is found to be 3Πu(0−u). The experimentally observed electronic absorption spectra of In2 are reassigned to A(3Πg)←X(3Πu) (13 000 cm−1) and B(3Πg)←X(3Πu) (27 700 cm−1) transitions. The observed emission spectrum in the King furnace is assigned to the 3Σ−u–3Σ−g system. Spectroscopic properties and potential energy surfaces of 15 more electronic states are reported which are yet to be observed. The 0+g electronic states of In2 exhibit considerable spin–orbit contaminations and avoided crossings resulting in double minima in the 0+g and 0+g(III) surfaces. The 3Σ+u(II) curve also undergoes an avoided crossing. The Mulliken population analyses of the electronic states of In2 are reported.