The existence of atomic-like states of silicon in siloxanic networks: a DFT approach

In this paper, we intend to demonstrate the possible presence of atomic-silicon cryptates in siloxanic networks by using a density functional approach. Since model molecules have been employed to model the candidate sites to host atomic silicon, we found that metastable adducts can be formed only in regions where the siloxanic network is not sub- jected to steric constraints; differently, stationary states are unstable in highly reticulated siloxanic networks. Our con- clusions reveal that Si atom is kept at the surface in atomic-like configuration by sigma charge donation from oxo-oxygen atoms into the empty Si psigma orbital and by pi charge back-donation from singly occupied Si 3pp orbitals into empty sigma* model molecule orbitals.