Condensed phase strategy

The condensed phase strategy includes the described mechanism of removal of heat and the enhancement of the decomposition temperature as in heat resistant fibres. In Table 8.1 the condensed phase and the gas phase mechanisms are compared. 

To our knowledge, the question of the standard state corrections in DSC experiments has never been addressed. These corrections may in general be negligible, because most studies only involve condensed phases and are performed at pressures not too far from atmospheric. This may not be the case if, for example, a decomposition reaction of a solid compound that generates a gas is studied in a hermetically closed crucible, or high pressures are applied to the sample and reference cells. The strategies for the calculation of standard state corrections in calorimetric experiments have been illustrated in chapter 7 for combustion calorimetry. 

These results suggest a computational strategy for the study of reactions in condensed phases. One starts from some realistic intermolecular potentials and performs a molecular-dynamics-Kramers-Grote-Hynes scheme that consists of the following steps.First, we fix the proton at the transition state and run a MD simulation. The friction kernel y(t) is calculated and along with Eqs. (7,8) enables the calculation of the Grote-Hynes rate. This scheme has also been used as a means of obtaining input for quantum calculations as well. ... 

The strategy which is commonly followed in the QM calculation of vibrational spectra of systems in a condensed phase is to start from the theory developed for isolated systems and to supplement that theory with solvent specificities. 

In many cases, the spectra recorded for the condensed phase are similar to those recorded in the liquid phase, but they usually contain a wider range of information than is available in liquid NMR spectroscopy. The solid state represents the best environment for the investigation of intermolecular interactions. Analysis of the tensorial nature of the chemical shifts provides subtle structural information. Strategies based on dipolar recoupling and /-coupling indicate a number of ways in which direct and indirect coupling constants can be measured, to yield direct structural constraints. This approach, combined with advanced theoretical calculations, traces new trends in structural studies of the condensed matter. 

New Computational Strategies for the Quantum Mechanical Study of Biological Systems in Condensed Phases... 

B. In their analytical model, WSB used zero-order reaction kinetics for the first reaction and obtained the steady state solution to the resulting set of algebraic equations by iteration using both reactions. However, our model starts from igniting the pure HMX solid by a constant (simulated laser) heat flux, and we have experimented with different types of kinetics for the first (condensed phase) reaction. This strategy allows us to represent the solid-gas interface as a structured region in one dimension, as opposed to a discontinuous boundary. 

Figure 6.2 Schematic illustration of the strategies used to obtain computational forms for fugacities, which are needed for phase- and reaction-equilibrium calculations. Traditionally, route 2A has been mostly used for gases, while route 2B was confined to condensed phases. However, these uses were dictated, not by thermodynamic limitations, but by limitations of the models used to correlate the data.

Strategy We are asked to predict, not calculate, the sign of entropy change in the reactions. The factors that lead to an increase in entropy are (1) a transition from a condensed phase to the vapor phase and (2) a reaction that produces more product molecules than reactant molecules in the same phase. It is also important to compare the relative complexity of the product and reactant molecules. In general, the more complex the molecular structure, the greater the entropy of the compound. 

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