Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects

Abstract

Mass spectrometry experiments show an exceptionally weak bonding between Si₇Mn⁺ and rare gas atoms as compared to other exohedrally transition metal (TM) doped silicon clusters and other Si_nMn⁺ (n = 5–10) sizes. The Si₇Mn⁺ cluster does not form Ar complexes and the observed fraction of Xe complexes is low. The interaction of two cluster series, Si_nMn⁺ (n = 6–10) and Si₇TM⁺ (TM = Cr, Mn, Cu, and Zn), with Ar and Xe is investigated by density functional theory calculations. The cluster–rare gas binding is for all clusters, except Si₇Mn⁺ and Si₇Zn⁺, predominantly driven by short-range interaction between the TM dopant and the rare gas atoms. A high s-character electron density on the metal atoms in Si₇Mn⁺ and Si₇Zn⁺ shields the polarization toward the rare gas atoms and thereby hinders formation of short-range complexes. Overall, both Ar and Xe complexes are similar except that the larger polarizability of Xe leads to larger binding energies.