Molecular orbital techniques, high

Methods based on simulated Ab initio Molecular Orbital technique (SAMO) or cm the application of Linear Combination of Localized Orbitals have been proposed. The a priori advantages are a negligible cost (typically of the order of magnitude of an extended Huckel calculation) and the ab initio character of the approach. They suffer however from a rather tedious generation of a high number of matrix elements and it is still impossible to... 

In spite of the minimal applications of computational chemistry to the chemistry of wood, the techniques have become highly developed and sophisticated in their ability to calculate chemical properties for a wide variety of compound classes. Methods based on quantum mechanics, commonly referred to as molecular orbital calculations, have been the topic of numerous books, reviews, and research papers (7,8,9,10). These techniques are concerned with the description of electronic motion, and the solution of the Schrddinger equation to determine the energy of molecular systems. Since the exact solution of the Schrddinger equation is only possible for two-particle systems, approximations must be invoked for even the simplest organic molecules. 

Drs. Larry A. Curtiss, Paul C. Redfern, and David J. Frurip present a tutorial on how to compute enthalpies of formation in Chapter 3. Often a computational chemist will want to know how stable a molecule is. The techniques described in this chapter can answer this question. The authors, who have studied what has been called computational thermochemistry, describe ab initio molecular orbital methods (including the highly accurate and popular Gn methods), density functional methods, semiempirical molecular orbital methods, and empirical methods (such as based on bond energies). These methods are richly illustrated with detailed, worked out examples. 

Kumar et al used spectroscopic techniques such as NMR to study the properties and structures of mixed glass systems. Rosenhahn et al. obtained insight into the structure and dynamics of the binary As-Se glass system from high temperature Se NMR studies of molten salts. Ab initio molecular orbital calculations have been carried out for sihcate, aluminosilicate and aluminate clusters to study the NMR characteristics of various types of hydroxyl that are possibly present in hydrous silicate glasses and melts. Xue and Kanzaki in particular studied the specification and dynamics of dissolved water in the silicate glasses. 

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