Atom, insides electronic structure

Optical spectroscopy also provides an excellent tool with which to obtain information on the electronic structure of absorbing/emitting centers (atoms, ions, defects, etc.), their lattice locations, and their environments. In other words, optical spectroscopy allows us to Took inside solids by analyzing the emerging light. 

The applicability of the discussed two-step algorithms for calculation of wavefunctions of molecules with heavy atoms is a consequence of the fact that the valence and core electrons may be considered as two subsystems, interaction between which is described mainly by some integrated properties of these subsystems. The methods for consequent calculation of the valence and core parts of electronic structure of molecules give us a way to combine the relative simplicity and accessibility both of molecular RFCP calculations in gaussian basis set, and of relativistic finite-difference one-center calculations inside a sphere with the atomic core radius. 

By the MEM charge density studies, the different features of encapsulated metal atoms in C82 were revealed for La C82 [2] and Sc C82 [3]. To compare the three-dimensional shape of the metal-atom charge distribution, a section of the equi-density surface of a La C82 molecule is presented in Fig. 9 together with the result for Sc C82 (Isomer I). The equi-density level is 1.8 e/A3. The number of electrons belonging to the Sc atom of Sc C82 was 18.8(2) e, which is close to the 19.0 e of a divalent state of the scandium atom, Sc2+. This indicates that the Sc C82 (I) is an endohedral metallofullerene whose formal electronic structure is Sc2+C82. This result has brought the long discussion as to whether the Sc atom is in a divalent or trivalent state inside the carbon cage [26-29] to an end experimentally. 

The above-mentioned three clusters, B6, Bi2-co, and Bi2-ico in Figure 8.1, have a hollow at the center of the cluster cages, which can be occupied by another atom. Fujimori and Kimura [5] reported that the Bi2-ico cluster with an additional B atom in its hollow site showed metallic bonding, instead of covalent bonding like the original Bi2-ico. In addition, recently the electronic structure of A B12-ico (A=H-He) clusters was studied by Hayami [6]. Boron clusters have been studied extensively as components of new materials. However, these studies have all focused on bare clusters, i.e., there is no reports on the electronic structure of boron clusters in c-Si with another element inside its hollows. 

The simplest explanation26 is to note that the transition structure for conrotatory opening with a filled p orbital inside 6.316 has a three-atom, four-electron conjugated system, which will be anti-aromatic, whereas an empty orbital inside 6.317 has a three-atom, two-electron conjugated system, which will be aromatic. Houk s calculations indicate that there is very little involvement of the p orbitals of the 7i bond in the transition structure, but even if they are included, the... 

Surface states can arise simply because the atomic bonding at a semiconductor surface is necessarily different from that in the bulk. For example, in a Si lattice, the bonds at the Si surface are not ftilly coordinatively saturated. To relieve this unsaturation, either a surface reconstruction can occur and/or bonds to the metallic material can be formed. This distinct type of surface bonding results in a localized electronic structure for the surface which is different from that in the bulk. The energies of these localized surface orbitals are not restricted to reside in the bands of the bulk material, and can often be located at energies that are inside the band gap of the semiconductor. Orbitals that reside in this forbidden gap region are particularly important, because they will require modifications of our ideal model of charge equilibration at semiconductor/metal interfaces. ... 

In general, electrochemical studies of Cg2 have been devoted to the study of its endohe-dral metallo complexes, in which metal atoms are trapped inside the fullerene cage. Part of the fascination with these molecules stems from two aspects of their electronic structures (1) Unlike noble gas endofullerenes, metallofullerenes are formed from a stable ion-pair association between a fulleride anion of charge n and a cation of charge n, which cannot escape from the anionic cage nor react with other substances outside the... 

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