Cagelike ${\mathrm{Au}}_{32}$ detected in relativistic density-functional calculations of optical spectroscopy

The optical absorptions of different ${\mathrm{Au}}_{32}$ isomers in the whole frequency range from the far-infrared (FIR) to near-ultraviolet (UV) have been calculated using the relativistic density-functional method in order to identify their geometrical structures. It is found that there exists a distinctive difference between the absorption spectra of the icosahedral cage-like ${\mathrm{Au}}_{32}$ and its amorphous isomers. The former shows significant absorption peaks in the visible and near-UV range, and a characteristic FIR-active mode at $46{\mathrm{cm}}^{-1}$, making it possible to be distinguished from others, which suggests that the optical spectra can thus be used as an efficient experimental tool to detect the “golden fullerene.”

Figure 1

(Color online) Calculated optical absorption spectra of the cage-like (left) and space-filled (right) ${\mathrm{Au}}_{32}$ isomers. The corresponding geometries and the relative energies to the icosahedral cage are also shown in each panel.

Figure 2

(Color online) DID, VDOS, and the calculated FIR absorption spectra for the lowest energy cage-like (a) (left panel) and space-filled (d) (right panel) ${\mathrm{Au}}_{32}$ indicated in Fig. 1. The shaded areas describe the IR spectra. The VDOS and FIR spectra were obtained by a convolution with a Lorentzian broadening of $2{\mathrm{cm}}^{-1}$.

Figure 3

(Color online) Calculated optical absorption spectra for two different ${\mathrm{Au}}_{42}$ isomers: (a) The icosahedral cage and (b) the space-filled structure. The corresponding configurations are drawn in each panel. Insets are the distribution of interatomic distances for them.