Spectroscopic properties and potential energy surfaces of In2

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 3Pi/sub u/(0-/sub u/). The experimentally observed electronic absorption spectra of In2 are reassigned to A(3Pi/sub g/)left-arrowX(3Pi/sub u/) (13 000 cm-1) and B(3Pi/sub g/)left-arrowX(3Pi/sub u/) (27 700 cm-1) transitions. The observed emission spectrum in the King furnace is assigned to the 3Σ-/sub u/--3Σ-/sub g/ system. Spectroscopic properties and potential energy surfaces of 15 more electronic states are reported which are yet to be observed. The 0+/sub g/ electronic states of In2 exhibit considerable spin--orbit contaminations and avoided crossings resulting in double minima in the 0+/sub g/ and 0+/sub g/(III) surfaces. The 3Σ+/sub u/(II) curve also undergoes an avoided crossing. The Mulliken population analyses of the electronic states of In2 are reported