Electronic structure and chemical bonding in W2 molecule

The electronic structure of the lowest-lying electronic states of W2 were investigated at the CASPT2 level. The ground state is a X 1 Σ g + state, followed by the a 3 Δ u , b 3 Σ u + and A 1 Δ u electronic states. Seven low-lying Ω -states were computed: ( 1 ) 0 g + , ( 2 ) 3 u , ( 3 ) 2 u , ( 4 ) 1 u , ( 5 ) 0 u - , ( 6 ) 1 u , and ( 7 ) 2 u , with the ground state corresponding to the ( 1 ) 0 g + ( X 1 Σ g + ) state. Comparison with the other VIB transition metal group dimers indicates a common pattern of electronic structure and spectroscopic properties.