To determine the vertical excitation energies, which have been extensively discussed in previous studies, the molecular structure was treated as a linear molecule with a center of symmetry, and the two U-O bond lengths were fixed at 1.708 Å. In addition to the ground state (Ω = 0g), the following excited states were calculated: 1g, the first and second solutions of 2g (hereinafter referred to as 2g(1) and 2g(2)), 3g(1), 3g(2), and 4g.