Charge-Transfer Excitations in Uranyl Tetrachloride ([UO2Cl4](2-)): How Reliable are Electronic Spectra from Relativistic Time-Dependent Density Functional Theory?

Four-component relativistic time-dependent density functional theory (TD-DFT) is used to study charge-transfer (CT) excitation energies of the uranyl molecule as well as the uranyl tetrachloride complex. Adiabatic excitation energies and vibrational frequencies of the excited states are calculated for the lower energy range of the spectrum. The results for TD-DFT with the CAM-B3LYP exchange-correlation functional for the [UO