Theoretical investigations of the structure and reactivity of the silicon(100) and germanium(100) surfaces: A study with density functional theory

The structure and reactivity of the germanium (100) surface has been investigated via density functional theory calculations. Comparisons to the structure and reactivity of the Si(100) surface are examined and detailed throughout the study. A central component of the reactivity of both surfaces is the dynamic buckling of the respective surface dieters. This effect is explored and correlated with the reactive adsorption mechanism of H₂ O on the Ge(100) surface. In order to facilitate a better understanding of this mechanism, the Si(111) and Si(111):H surfaces were examined to determine if the presence of a single dangling bond is sufficient to initiate unactivated dissociation of the H₂O molecule. A further description of the reactive model of the Ge(100) surface is illustrated by the interaction of the surface with the unsaturated hydrocarbons ethylene, 1,3-butadiene and 1,3-cyclohexadiene. Reaction of the hydrocarbons occurs via interaction of the adsorbate with the weak π-bond of the surface dieter similar to C=C double bond chemistry. A novel Diels-Alder addition of 1,3-butadiene across two dimers is discussed for the Si(100) surface and proposed as a possible competing reaction mechanism for adsorption of the conjugated diene.