Molecular solids, changes

The next step is to assume particular functional forms for the various terms. These can be extremely elaborate, but most are usually based on a simple, chemically intuitive model of the interactions, e.g. stretching of bonds, changes in bond and torsion angles, Coulomb forces and van der Waals intermolecular interactions. Thus, for a molecular solid comprised of discrete molecules, we might well use... 

Impact of LEE on atomic and molecular solids has been observed to induce chemical changes other than dissociation. In the next two sections, we will review examples of electron-induced reactions that proceed via formation of a TNI. 

The transducing mechanism of semiconductor luminescence involves the modification of the semiconductors surface electrical properties through molecular adsorption. Changes in solid-state electro-optical properties result from adsorption of the molecule of interest onto the semiconductor surface. 

To predict the sign of A S, look to see if the process involves a phase change, a change in the number of gaseous molecules, or the dissolution (or precipitation) of a solid. Entropy generally increases for phase transitions that convert a solid to a liquid or a liquid to a gas, reactions that increase the number of gaseous molecules, and dissolution of molecular solids or salts with +1 cations and —1 anions. 

The molecular structure of the solid does not change with physisorption except for some molecular solids (e.g. ice, paraffin, polymers). 

In this article, we shall discuss studies of phase changes in solids carried out by the application of the generalized Monte Carlo and the molecular dynamics methods. This topic is of particular significance because of the recent modifications of the method to include both variation in size and shape of the simulation cell. What is especially gratifying is that we are now able to make meaningful predictions of phase transitions in real solids by employing reliable pair potentials. Besides phase transitions of molecular solids, we shall examine phase transi-... 

A variety of solid materials, including metals, semiconductors, molecular solids, and ionic compounds, show a remarkable deviation from the simple Hooke s law in the pressure dependence of volume at 1-lOGPa. The deviation is quite often a prelude to a pressure-induced transition to a denser structure. - " For example, Fe metal changes its strac-ture from cubic (a-phase) to hexagonal (e-phase) at 11 GPa... 

Figure 5.7 Solid bilayer helices slowly add material to the curved edges and finally form tubules. Neither the pitch nor the width of the molecular assembly change significantly.

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