Intra binding energy

Much of this book is concerned with the properties of narrow bands to which the tight-binding approximation is appropriate. In this case, if the band is half full or nearly so, the short-range repulsion between the electrons may have very important effects on the properties of the electrons in the bands, producing magnetic moments and non-conducting properties. These are a major theme of this book. At this point we introduce the Hubbard intra-atomic energy ... 

In the case of La, Ce, Pr and Nd, a weak band on the lower binding energy side of the 3d band has been observed. The XPS of Ba, La, Ce and Pr are shown in Fig. 9.14. The observed weak band has been attributed to charge transfer from the conductance band (6s, 5d) to the 4f level. In this case, the 3d hole is thought to stabilize the 4f level as compared to the conduction band (6s, 5d) thereby facilitating the intra-atomic charge transfer process. 

Here L is a correction of the Mulliken approximation for the kinetic energy and All is entirely empirical and contains adjustable bond parameters. These are optimized in order to minimize the deviation from experiment for a set of reference compounds. In a way similar to INDO/S [Eq. (45)], two sets of Slater orbital exponents are used one K(0)] for intra-atomic integrals and the other (0 for molecular integrals. For comparison with experimental heats of formation, the calculated binding energies Eb [Eq. (4)] are corrected by the zero-point energies obtained from vibration analyses. Later, a substantially modified version of SINDOl, MSINDO, was developed and reparameterized for the elements H, C F, Na-Cl, Sc-Zn, and Ga-Br [63-65],... 

Core binding energies also differ from the Koopmans estimate, the negative of the core orbital energy. When an inner electron leaves an atom of a molecule, the outer orbitals readjust because the nuclear charge is less effectively screened. The change due to outer shell readjustment is known as intra-atomic (or intramolecular) relaxation energy. 

The ESCA method is applicable for processes occurring within time periods of 10 sec, so ionic species can be characterized regardless of their intra- and intermolecular interactions, e.g., Wagner-Meerwein rearrangements, hydride shifts, etc. The method permits the carbon Is binding energy shifts to be measured directly. 

The well-known BE difference between XPS signals of metal ions in their oxides and in zeolites [33,35] has frequently been used to prove the intra-zeoHte location of species. Higher BE values observed with zeolites have been attributed to the influence of intra-crystalHne potentials, in some cases also to final-state effects (La, Cu, vide infra). In view of the considerable variation in the Na Is BE with the fi amework Al content [7-9,11,12] it may be expected that the binding energies of other metal ions will also depend on the Al/Si ratio. This has recently been confirmed for VO + ions [106], but a systematic study of this problem is not yet available. The BE of metal ions in zeoHtes are sometimes close to those in the corresponding hydroxides (e.g., Ni +, Cu +, Co +), so that discrimination between extra- and intra-zeolite locations on the basis of XPS binding energies alone is not safe. Thus, it has been found that the Cu 2p BE of Cu(II) oxide species well... 

Several groups found that intra-framework Fe(lII) exhibits Fe 2p binding energies higher than Fe203 as well, although the situation is comphcated as... 

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