Various possible reaction channels of U atom with CO molecule have been presented based on relevant experimental results. The geometry structure, harmonic frequency and total energy of all species have been calculated and studied by the first principle, and the calculated results show that CUO and (η²-C₂)UO₂ are the stable products in the primary and secondary reaction. Attacking CO from C atom or side position by U atom has been presented as the most possible reaction channel, and reaction mechanism has also been explained by molecular orbital theory.

Key words: molecular orbital theory, the first principle, reaction channel