Angular overlap model calculations

In recent studies, involving the prediction of electronic and EPR spectra of hex-aamine complexes of chromium(III), low spin iron(II), cobalt(III), nickel(II) and copper(II)[90,166,197,3021 with a combination of molecular mechanics and AOM (angular overlap model) calculations, the two effects could be separated (Table 10.4 see also text below) because the structural factors (steric crowding molecular mechanics) and the electronic factors (inductive effects AOM) are parameterized separately. 

P. V. Bernhardt and P. Comba, Inorg. Chem., 32,2798 (1993). Prediction and Interpretation of Electronic Spectra of Transition Metal Complexes via the Combination of Molecular Mechanics and Angular Overlap. Model Calculations. 

Numerous applications of [Cr(NH3)6]3+ and its derivatives to mechanistic studies of conventional or photo-assisted ligand-exchange reactions have been extensively reviewed.7,270-276 Among other common Cr111 complexes, [Cr(NH3)6]3+ has been used for the studies of reactivities of muonium and positronium atoms in aqueous solutions.313-315 Several computational methods, including DFT calculations,316 a combination of molecular mechanics and angular overlap model calculations, or vibrational analysis have been used for the prediction and interpretation of electronic spectra and photochemical properties of [Cr(NH3)6]3+. 

Relativistic electronic structure calculations on molecules containing lanthanide elements, published after 1987. Ligand held and angular overlap model calculations are not included... 

Calculations of the Jann-Teller coupling constants for dx systems in octahedral symmetry via the angular overlap model. K. D. Warren, Struct. Bonding (Berlin), 1984, 57,119 (20). 

Crystal field splitting parameter, 2, 309 Crystal field theory, 1, 215-221 angular overlap model, 1, 228 calculations, 1, 220 generality, 1,219 low symmetry, 1,220 /-orbital, 1, 231 Crystal hydrates, 2, 305,306 bond distances, 2, 307 Crystals... 

Warren KD (1984) Calculations of the Jahn-Teller Coupling Constants for d Systems in Octahedral Symmetry via the Angular Overlap Model. 57 119-145 Warren KD (1977) Ligand Field Theory off-Orbital Sandwich Complexes. 33 97-137 Warren KD (1976) Ligand Field Theory of Metal Sandwich Complexes. 27 45-159 Watson RE, Perlman ML (1975) X-Ray Photoelectron Spectroscopy. Application to Metals and Alloys. 24 83-132... 

Warren, K. D. Calculations of the Jahn-Teller Coupling Constants for d Systems in Octahedral Symmetry via the Angular Overlap Model. Vol. 57, pp. 119-145. 

The term angular overlap model was first used in 1965 to describe a more general treatment, which may also be called the model (12,13). The relative energies of the orbitals in a partly-filled /-shell are expressed in terms of the parameters ex (X = a, rr, etc.), whose coefficients can be calculated from the geometry of the system. The eK model was developed from perturbation theory, but is equivalent to the E2 model when only a-overlap is considered, and to the Yamatera-McClure model for orthoaxial chromophores with linear ligators. The notation ex is often used, where ... 

Distortion of coordination polyhedra is commonly observed in silicates. Because distortion of the coordination field implies elimination of degeneracy, it is important to evaluate to what extent the nondegenerate condition contributes to the stability of the phase. Systematic MO calculations in this direction have been carried out by Wood and Strens (1972) on the basis of the AOM (Angular Overlap Model) integrals of Ballhausen (1954). 

Hiickel calculations have been employed extensively in other approaches such as the angular overlap model and the method of moments developed by Burdett and coworkers. Stabilities of crystal structures, pressure- and temperature-induced transitions, dynamical pathways in reactions and other phenomena have been analysed using angular overlap models. Thus, the electronic control of rutile structures and the stability of the defect structure of NbO have been examined (Burdett, 1985 Burdett Mitchell, 1993). In the case of NbO, the structure is stable at involving the formation... 

In situations where maximum overlap criteria are important, it is often possible to construct simple perturbation theory arguments to account for broad geometric trends. Burdett has illustrated in a very neat fashion how the geometries of binary metal carbonyls M(CO) may be rationalized using such an angular overlap model (55). The same problem has also been tackled by Elian and Hoffmann using more complete extended Hiickel calculations (78). 

As a last remark, it should be mentioned that also a few evaluations of the crystal-field parameters of Pr3"1" in LaCH in the scope of the angular overlap model have been made. Urland et al. (1985) andUrland (1989) used the angular overlap model to calculate the crystal-field splittings of LaCHiPr3"1" under pressure. In addition, Gregorian et al. (1989) derived the parameters of both models and found that both approaches were capable to successfully describe the high-pressure results. 

The Angular Overlap Model and the Influence of Madelung Potentials on Wolfsberg-Helmholz Calculations... 

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