Structures, stabilities, and electronic properties of the neutral and anionic Si _n Sm^λ (n = 1–9, λ = 0, −1) clusters: comparison with pure silicon clusters

Abstract

Geometric structures, stabilities, and electronic properties of Si ^λ _n+1 and Si _n Sm^λ (n = 1–9, λ = 0, −1) clusters have been investigated systematically using density functional method at four levels. Extensive searches for ground state structures were carried out by the comparison between simulated spectra and the measured photoelectron spectroscopy. The results show that Sm atom tends to occupy the low-coordinated position and edge-cap or face-cap on the silicon frames. The lowest energy structures of Si _n Sm^0/− favor planar structures for n = 1–3 and three-dimensional structures for n = 4–9. Based on the averaged binding energies and fragmentation energies, we predict that Si₄Sm and Si₂Sm⁻ clusters have the higher relative stabilities. Furthermore, the patterns of HOMOs and derivatives of ρ for the most stable doped isomers are investigated to gain insight into the nature of bonding. The result shows that π-type or σ-type bonds are always formed among the Si atoms, and the interaction between the Sm and Si atoms is very weak. To achieve a deep insight into localization of charge and reliable charge-transfer information, the Mulliken population are analyzed and discussed. In addition, the electrostatic potential, which is well established as a guide to the interpretation and prediction of molecular behavior, is performed for the lowest energy structures of Si _n Sm^λ (n = 1–9, λ = 0, −1) clusters.