Clusters configuration

1 Relationships Between Ligand Arrangement and Direct Inter-cluster Linkages 

The ligand arrangement in these oxychlorides leads to equivalent coordination of all niobium atoms, which correlates with the formation of structures containing discrete clusters. 

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NakatsujI H and Nakal H 1990 Theoretical study on molecular and dissociative chemisorptions of an O2 molecule on an Ag surface dipped adcluster model combined with symmetry-adapted cluster-configuration interaction method Chem. Phys. Lett. 174 283-6... 

The structures observed in the mass spectra of fullerene molecules covered with alkaline earth metals, as described in the previous section, all seem to have a geometric origin, resulting in particularly stable cluster configurations every time a highly symmetrical layer of metal atoms around a central fullerene molecule was completed. When replacing the alkaline earth metals by an alkali metal (i.e., Li, Na, K, Rb, or Cs), a quite different situation arises. 

Connections between Coupled Cluster, Configuration Interaction and Perturbation Theory... 

COUPLED CLUSTER, CONFIGURATION INTERACTION AND PERTURBATION THEORY... 

The in-line configuration consists of deposition chambers that are separated by isolation chambers [153]. The layer sequence of a solar cell structure prescribes the actual sequence of deposition chambers. The flexibility is much less than with a cluster configuration, and costs are generally much higher, but the throughput can also be much larger. In an in-line system the substrates can move while deposition takes place, which leads to very uniformly deposited layers, as uniformity of deposition is required only in one dimension (perpendicular to the moving direction). 

This model of the receptor-bound conformation of TIP is characterized by a clustered configuration of the three aromatic moieties with the Phe3 aromatic ring sandwiched between the Tyr1 and Tic2 aromatic rings. 

In this chapter, we will study the elementary reaction steps of these mechanisms focusing primarily on the anthraphos systems. This chapter begins with a description of the impact of different methods (coupled cluster, configuration interaction and various DFT functionals), different basis sets, and phosphine substituents on the oxidative addition of methane to a related Ir system, [CpIr(III)(PH3)Me]+. Then, it compares the elementary reaction steps, including the effect of reaction conditions such as temperature, hydrogen pressure, alkane and alkene concentration, phosphine substituents and alternative metals (Rh). Finally, it considers how these elementary steps constitute the reaction mechanisms. Additional computational details are provided at the end of the chapter. 

Cluster Configuration Peripheral Bonds Delocalized (r-honds Delocalized ir-bonds Antiaromaticity... 

The validity discriminant discussed in this section is the descendant of an earlier cluster validity measure used by Gunderson ( ) to assess the quality of cluster configurations obtained in an application of the Fuzzy ISODATA algorithms. It is closely related to a method suggested by Sneath ( ) for testing the distinctness, i.e. separation, of two clusters, and also borrows from the ideas of Fisher s linear discriminant theory (see chapt. 4, Duda and Hart,(2 0). The validity discriminant attempts to measure the separation between the classes of a cluster configuration usually, but not necessarily, obtained by application of the FCV algorithms. A brief description follows ... 

In the next step, the similarity between the sampling sites was investigated using SOM. Different values of k (a predefined number of clusters) were tried and the sum of squares for each run was calculated. Finally, the best classification with the lowest Davies-Bouldwin index (also shown graphically in Figure 15.8) was chosen. It is seen that the five-cluster configuration has the lowest... 

Ce enters the CaF2 lattice substitutionally for the host Ca ions. Several site symmetries are possible depending upon the charge compensation. Non-locally compensated Ce + produces a center of 0 symmetry, whereas C4v symmetry results when F" ions in interstitial positions take up nn positions to the impurities along <110> directions. In addition many higher-order cluster configurations of these impurity-interstitial pairs exist (23). 

Quadratic Configuration Interaction with Singles and Doubles Quadratic Configuration Interaction with Singles, Doubles, and Noniterative Approximation of Triples Symmetry Adapted Cluster-Configuration Interaction Split-Valence basis set plus Polarisation functions Zero-Order Regular Approximation Zero-Point Energy... 

SAC-CI Symmetry-adapted-cluster configuration-interaction TDDFT Time-dependent density-functional theory TDHF Time-dependent Hartree-Fock... 

The plan of this chapter is as follows. The next section briefly reviews the CC formalism for the ground state. This is necessary since the LR-CC and EOM-CC approaches start from the CC ground state description. It also introduces some notation that will be used in later sections. Next, the basics of the exact EOM-CC approach are derived, showing how an eigensystem is arrived at. After some aspects of characterizing an electronic transition, EOM-/LR-CC methods that have been developed and implemented are surveyed. The next section presents a numerical assessment of some of the main methods. Finally, a few illustrative applications are summarized. Some aspects of EOM-CC methods are discussed in Chapter 2. The symmetry-adapted cluster configuration interaction (SAC-CI) method can be related to EOM-CC methods. The SAC-CI method and several impressive applications thereof are described in Chapter 4. 

Nakatsuji H, Hasegawa J, Hada M (1996) Excited and ionized states of free base porphin studied by the symmetry adapted cluster-configuration interaction (SAC-CI) method. J Chem Phys 104 2321-2329. 

EXPLORING PHOTOBIOLOGY AND BIOSPECTROSCOPY WITH THE SAC-CI (SYMMETRY-ADAPTED CLUSTER-CONFIGURATION INTERACTION) METHOD... 

The astute reader will recognize that this compound is a metal-metal bonded adaptation of the well-known hollandite structure (19). Further, the metal cluster configuration is like that in CsNb Cl.. (20), though the latter compound possesses a double layer structure rather than the tunnel structure observed here. Finally these new structures provide only a glimpse of what is possible, and an excitement about new compounds of unusual structure and properties yet to come from studies of highly reduced ternary and quaternary refractory metal oxide systems. 

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