Abstract: The low-lying electronic excited states of M2Cl4(PMe3)4 and M2(O2CCH3)4 (M = Mo, W) have been studied using the time-dependent density functional theory (TDDFT). Furthermore, the applicability of a series of functionals, such as LDA, GGA and hybrid functional, for calculating d-d and charge-transfer (CT) transitions of quadruply bonded metal compounds have been tested. It is found that the LDA and GGA functionals provide accurate description of the d-d transitions, but yields substantial errors for the excitation energies of CT transitions. The electrostatic attraction between the separated charges in long-range excited charge-transfer states originates from the non-local Hartree-Fock exchange potential and is a non-local property. Present-day TDDFT method employing pure exchange-correlation functionals (LDA or GGA) does not capture this effect and therefore fails to describe CT excited states correctly. The hybrid functionals include parts of HF exchange provide accurate results for the CT transition energy, but the errors in the d-d transition energies were much larger than those predicted by the LDA and GGA functionals. In order to simultaneously obtain the accurate descriptions of both d-d and CT transitions of quadruply bonded metal compounds, we will look forward to the strict time-dependent non-local functional is applied to the calculation of TDDFT method.

Key words: quadruply bonded metal compound, time-dependent density functional theory, electronic spectrum, d-d transition, charge-transfer transition