Bonding properties and isomeric conversion pathways of singlet BeSi4 clusters

Structures of several singlet BeSi4 clusters including transition state complexes were obtained at the level of B3LYP/6-311++G(3df). All have a tiny positive charge on Be, implying a covalent nature in Be–Si bonds that agrees with the small electronegativity difference between the two elements. Most species also have a hypervalent Be atom that may be associated with the high reactivity of Be on the Si(1 1 1) surface observed by Hite et al. Feasible entrance channels for neutral Be + Si4 have been provided and the transition states for isomeric conversion were confirmed. Mayer bond orders together with energetic diagram and geometrical parameters serve to illustrate the conversion progress.