Crystallization research background

Readers of different backgrounds will wish to follow different paths through the chapters. Both the engineer and the researcher may wish to read Chapter 1 that provides a historical overview of clathrate hydrates. One cannot deal with hydrates without some knowledge of the all-important crystal structures provided in Chapter 2. Chapter 3 on hydrate kinetics gives the current picture ofhydrate time-dependence to supplement the time-independent phase equilibria in Chapter 4, the last chapter that should be of common interest to both the engineer and the... 

Quantum Systems in Chemistry and Physics encompasses abroad spectrum of research where scientists of different backgrounds and interestsjointly place special emphasis on quantum theory applied to molecules, molecular interactions and materials. The meeting was divided into several sessions, each addressing a different aspect of the field 1 - Density matrices and density functionals 2 - Electron correlation treatments 3 - Relativistic formulations and effects 4 - Valence theory (chemical bond and bond breaking) 5 -Nuclear motion (vibronic effects and flexible molecules) 6 - Response theory (properties and spectra) 7 - Reactive collisions and chemical reactions, computational chemistry and physics and 8 - Condensed matter (clusters and crystals, surfaces and interfaces). 

It is beyond the scope of this review to be exhaustive in the field of supercooled liquids that has drawn intense research activities over several decades. Reviews that are exclusive for this field and deal with specific topics in considerable detail are recommended for supplemental reading [9-11]. In view of the scope this chapter, the next section provides the readers with a brief introduction to the systems of interest and associated nomenclature. Section III sets up the background by reviewing experimental results on the dynamics of thermotropic liquid crystals across the I-N transition, then introducing the central issues in the dynamics of supercooled liquids, and finally comparing the dynamics of the two systems in the light of recent experiments. Section IV presents a summary of some of the well-known theoretical approaches to liquid crystals. Section V provides a detailed account of computational efforts. Finally, we conclude in Section VI with a list of problems for future work. 

A number of models are associated with the typical behaviors of the substances, their level depending on the nature of the concepts and the degree of specificity held to be relevant. The hydrodynamic models do not lend themselves especially either to research on the azides or to detailed experimental investigations at the more fundamental level. Thus throughout the research described, the hydrodynamic theory has tended to remain in the background, and improved understanding has been sought at the crystal, molecular, and electronic levels. 

Unresolved Problems Against the background of above listed achievements, there are still some unanswered questions that appear in the course of the research. These include, in particular, the mechanism of condensation energy transfer from a low-volatility product to a reactant, and the influence of the symmetry of the reactant crystal structure on the composition of the gaseous decomposition products. It would be worthwhile to perform a more thorough analysis of the dependence of the t coefficient and the sizes of the condensate particles on the vapour oversaturation of the low-volatility product, as well as of the relative contributions of the condensation and self-cooling effects to the underestimation of enthalpies determined by the second-law and Arrhenius plot methods. 

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