Photoabsorption spectra of cationic mercury clusters

Abstract

The experimental photoabsorption spectra of singly charged cationic mercury clusters ($\mathrm{Hg}_{N}{}^{+}$) show a sharp change in behavior at cluster size $N=6$. Both relativistic density functional theory (DFT) and wave function based methods reveal that this corresponds to a structural change from linear to three-dimensional isomers. The simulated electronic excitation spectra obtained from time-dependent relativistic DFT agree well with the experimental results. Our quantum theoretical treatment confirms the change from single electron-hole excitations in small linear clusters to plasmonlike collective transitions for the larger three-dimensional clusters.