Oxygen basin populations

TABLE 3. Basin population of oxygen core, disynaptic and monosynaptic attractors. 

The topological analysis of the density and of the ELF funetion provides new information to understand the nature of the Si-0 bond. On the one hand, the atomic population and the bond ellipticities tell us that the SiO bond is partly ionic and also that there is no evidence for a partial double bond character. This latter point is confirmed by the analysis of the ELF function since there is only one attractor between the oxygen and silicon cores and that its basin population is always less than or equal to 2 electrons. Moreover, it appears more important to consider the oxygen than the silicon to discuss the bonding in silica. The Si-0 bond is found to belong to the electron shared interaction by the ELF analysis. 

In all these cases, ion-pair transition structures have been characterized, and the intimate nature of bonding has been discussed using the electron properties arising from ELF analysis. In particular, charge separations of 0.48e, 0.42e and 0.18e can be deduced from the basin structure and populations for the oxygen to oxygen, sulfur to oxygen and sulfur to sulfur proton-transfer transition states, respectively. 

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