The intensities associated with the excitation spectra were calculated using the oscillator strengths 𝑓 𝑎,𝑏 of an a → b electron transition, with a and b representing the initial final electronic states (in atomic units): 𝑓 𝑎,𝑏 = 2 3 ∆𝐸 𝑎,𝑏 ⟨𝑎|𝝁|𝑏⟩ 2 , where the electric transition dipole moments were formulated in the dipole-length form (𝝁 = -𝑟). The non-zero oscillator strengths for 5f-5f transitions arise from the mixing between actinide 5f states and 6d or other ligand states in a noncentrosymmetric ligand-field regime. The ligand states for the actinide complexes are referred to the one-electron ligand-to-metal charge transfer states that possess large parentage of ligands 2p orbitals. We note that we use a static model somewhat equivalent to the Judd-Ofelt model, where non-zero oscillator strengths existed through parity mixing that is due to the coordination geometry of the actinide ion. Thus, dynamical effects (eg. vibrations) were not considered in our calculations.