The electronic states of 1,2,5-oxadiazole studied by VUV absorption spectroscopy and CI, CCSD(T) and DFT methods

Complete minima were found after minor twisting of the structures. The lowest energy cationic state is 2A″ (CS), which closely resembles the 2B2 state. The O-N-C-C skeleton is twisted by 8°. The corresponding 2A′ state (CS) is effectively identical to the 2B1 state. Attempts to find minima for other symmetry states were unsuccessful.