Benchmarking HF Exchange in Simulated Spectra with TD-DFT of Ligand-Protected Noble Metal Clusters

Noble metal clusters with exceptional photophysical properties are promising luminescent materials, with TD-DFT calculations providing a vital approach to elucidating their luminescence mechanisms. However, the TD-DFT results are highly sensitive to the choice of exchange-correlation functionals, and benchmarking simulated absorption spectra is critical to validate computational methodologies. Since previous empirical screening of functionals is still lacking systematic guidance, this work systematically evaluates functional performance for simulating UV-vis absorption spectra of ligand-protected Au/Ag/Cu/Pt clusters via TD-DFT. Key findings confirm that the effect of the Hartree-Fock (HF) exchange composition on simulated spectra is dominant, irrespective of the type of hybrid functional. Benchmarks against experimental data further show that functionals incorporating 10-20% HF exchange deliver optimal spectral agreement. These insights identify HF exchange as the key determinant of TD-DFT accuracy for stimulating absorption spectra of noble metal clusters, providing a quantitative framework for predictive functional selection in the theoretical study of luminescent noble metal clusters.