Localized electron model three parts

This contrast is in part due to the difficulty of invoking fuzzy three-dimensional electron density clouds in a mechanistic interpretation of reactions, which is also hindered by the perceived classical nature of the concept of localization. Classical objects, often used in analogies when modeling molecular structures, usually exhibit localized features, yet the very concept of localization apparently conflicts with the delocalized nature of molecular electron distribution and the Heisenberg uncertainty relation. 

Three different but connected problems must be studied (i) the reaction kinetics model (ii) the development of the rate of electron-hole generation in a material particle of the solid suspension and (iii) the model for characterizing the radiation field to evaluate the local volumetric rate of photon absorption (LVRPA). Point (iii) has been already described in section 6.6.1 for quantum yield determinations. In the first part of this section, we will concentrate on problems (i) and (ii). 

Three reviews on transition metal dimers [1], molecules [2], and clusters [3] contain experimental and theoretical M2 data for M = Ru, Pd [1 to 3], Rh [1,3], Os, Ir [3], and Pt [2, 3]. A few abbreviations used in theoretical work, which are perhaps not as common as HF, MO, VB, SCF, EH, or CNDO and which are occasionally used in the following, are AE (all electron). Cl (configuration interaction), MC (multiconfigurational), MP (model potential), REP (relativistic effective potential), LSD (local spin density), SW (scattered wave), CAS (complete active space). Only part of the numerous theoretical and semiempirical investigations covering M2 are mentioned in this section. For the whole material, see list of theoretical work on M for all n at the end of the chapter. 

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