Static polarizabilities and optical absorption spectra of gold clusters (Au-n, n=2–14 and 20) from first principles
Idrobo, Juan C.
Yip, Shing Fan
PublisherAmerican Physical Society
MetadataShow full item record
Static polarizabilities and optical absorption spectra for the ground state structures of gold clusters (Au-n, [n is subscript] n=2-14 and 20) are investigated from first principles within static and time-dependent density functional theory. The static polarizabilities of clusters with less than 14 atoms generally increase as a function of size modulated by even-odd oscillations. The polarizabilities of Au-14 and Au-20 are noticeably lower due to the shape transition from two-dimensional to three-dimensional structures at n=14. The analyses of the optical absorption spectra calculated within the time-dependent local density approximation indicate that the d electrons in Au-n clusters are significantly more involved in low-energy transitions and give rise to more quenched oscillator strengths (by screening the s electrons) than in Ag-n clusters. These stronger effects of the d electrons in the optical properties of Au-n are due to the larger degree of proximity of the s and d levels in the Au atom as compared to the Ag atom, which gives rise to stronger s-(p)-d hybridization in the molecular orbitals of Au-n. The calculated spectra are found to be in good agreement with experimental data and results from earlier studies for the available sizes.
electronic photodissociation spectroscopy
2-photon ionization spectroscopy