Charge‐transfer processes in the assembly of Si_nO_m neutral clusters

Abstract

The chemical bond formation in oxygen-rich Si(n)O(m) clusters was investigated by sampling the potential energy surface of the model systems SiO + SiO(2) → Si(2)O(3) and (SiO)(2) + SiO(2) → Si(3)O(4) along a two-dimensional reaction coordinate, by density functional theory calculations. Evidence for crossing between the weakly bound neutral-neutral (SiO)(n) + SiO(2) and the highly attractive ion-pair (SiO)(n)(+) + SiO(2)(-) surfaces was found. Analysis of frontier molecular orbitals and charge distribution showed that surface crossing involves transfer of valence electron charge from (SiO)(2) to SiO(2). The sum of the natural atomic charges over the (SiO)(n) and (SiO(2)) groups of the Si(n)O(m) cluster products, gave a net positive charge on the (SiO)(n) "core" and a net negative charge on the (SiO(2)) groups. This is interpreted as the "ion-pair memory" left on the Si(n)O(m) products by the charge-transfer mechanism and may provide a way to assess the role of charge-transfer processes in the assembly of larger Si(n)O(m) neutral clusters.

Vibrational spectra and structures of neutral Si6X clusters (X = Be, B, C, N, O)

“…Whereas an enormous amount of theoretical work on small doped silicon clusters is available (e.g., ref. 12,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], only a few experiments have been reported in the gas phase. 8,14,[35][36][37][38] By sequential doping of silicon clusters with carbon atoms, i.e., for Si m C n with m + n = 6, we recently observed a systematic transition from one-dimensional geometries for pure C 6 to three-dimensional structures for pure Si 6 .…”