Electron capping principle

Wade s electron-counting procedures (22) start from a closed polyhedron and require that neither removing a vertex from this polyhedron nor capping a face will alter the number of skeletal bonding orbitals. This capping principle has been demonstrated to be general (31). For... 

Keywords Aluminum Capping principle Closed-shell principle Clusters Condensed clusters Copper Electron-counting rules Gallium Gold Jellium model Nanoclusters Palladium Polyhedral skeletal electron pair theory Silver Tensor surface harmonic... 

The Capping Principle has been derived for evaluating the electron count in condensed polyhedra from those of its component polyhedra. Thus, it has been established that the total electron count in a condensed polyhedron is equal to the sum of the electron count for the parent polyhedron minus the electron count characteristic of the atom, pairs of atoms, or face of atoms which are common to both polyhedra. The frontier orbitals of the capping fragment are matched in... 

A classical example of correlation of structure with valence electron count is shown in Fig. 2.34. There the structures of a series of osmium clusters are systematized by using the capping principle combined with the approach of decapping (i.e. removal of cluster vertices). 

How to cap the quantum calculation so that there are no dangling electron s or bonds in the quan turn m eeh an ical calculation wdi ilc still preservin g th c desired effect of the classical portion (which is now there, only in principle ). 

Figure 12 Principle of charge separation in semiconductor heterostructures (a) capped (or Core-Shell) geometry and (b) coupled geometry. Electrons accumulate at the conduction band (CB) of Sn02 while holes accumulate at the valence band (VB) of Ti02.

Fig. 8. Correlation of structure with valence electron count for transition metal cluster, utilising the Capping and Debor principles...

The condensation of octahedra via common vertices, edges or faces leads to cluster units of a type known since the end of the 1970 s. Among these are the metal-rich subhalides of the early transition metals [186-188] and the Chevrel phases. [179, 189-192] The preparation of [Co9Sen(PPh3)6] (46) (Fig. 3-66) made it clear that this structural principle could be extended to the more electron-rich transition metals. [164, 168] All faces of the C09 cluster in 46 are capped by either /ig-or / 4-Se ligands. The Co atoms of the basal faces (Col, Co4, Co9, C06, Co7,... 

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