Crystal geometry

Avrami exponent Crystal geometry Nucleation mode Rate determination Equation ... 

The X-ray diffraction method is applicable to solids and provides such detailed views of crystal geometry as those shown for sodium chloride solid in Figure 5-10, p. 81. 

The information stored in the specimen database is sufficient to identify the particular specimen and the material from which it is made. Other parameters provide information on the orientation of the specimen and on its unit cell parameters. These latter parameters are used by the data collection tasks and the crystal geometry calculation function to determine diffraction angles, the angles between crystal planes, etc. The user can store information on several specimens in the specimen database, thus permitting him to easily remount and rerun a specimen after looking at the collected data. 

Clearly, this equation can be made more precise by modifying the terms by reference to the crystal geometry. Additionally, the free energy term AGm can be separated into its components, using the following equation ... 

In order to consider the inversion of Qx(0,0) and Qy(0,0) electronic transition intensities in NH-tautomers of non-symmetrical free-base porphyrins we calculated the ground-state orbital energies of the investigated molecules by a CNDO/2 method using the symmetrized crystal geometry of porphyrin molecule (37,38). On the basis of the above experimental results we must introduce a motionless system of molecular X and Y axes, identically fixed in both tautomers. Then using theoretical MO calculations and the analysis... 

All quantities are given in units of 10 30 Cm (see Appendix K for conversion factors). The 6-31G ab-initio results have been obtained at the SCF level, generally at the neutron crystal geometry. DI direct integration. DB discrete boundary. FB fuzzy boundary, i.e.. stockholder concept. 

J.G. Amar and F. Family, Molecular beam epitaxy simulations with correct crystal geometry,... 

A small number of carbocations have been crystallized and their geometries determined by X-ray diffraction. Although the influence of counterions is of some concern, in many cases these can be made sufficiently bulky to preclude their encroaching too close. Here, the measured crystal geometry should closely reflect that of the (isolated) charged species. 

The restrictions on crystal geometry by relative ion sizes are not as severe. Comparing the illustrations of NaCl and CsCl, we see that there is a difference in the number of nearest neighbors that ions have in these structures. In NaCl each ion is surrounded by six other ions of opposite charge, whereas in CsCl each ion has eight nearest neighbors. Finally, in CaF2,... 

Excellent source for the facts of molecular and crystal geometry detailed discussions. 

Methods need to be developed to measure and determine the influences of factors such as strain, crystal geometry, dislocation density, low concentrations of coprecipitates, etc. on subtle solubility and reactivity differences of carbonate minerals. 

J. Caillet and P. Claverie, Theoretical evaluations of the intermolecular interaction energy of a crystal application to the analysis of crystal geometry, Acta Crystallogr. B, 34 (1978) 3266. 

I. Dqbkowska, H.V. Gonzales, P. Jurecka, P. Hobza, Stabilization energies of the hydrogen-bonded and stacked stmctures of nucleic acid base pairs in the crystal geometries of CG, AT, and AC DNA steps and in the NMR geometry of the 5,-d(GCGAAGC)-3 hairpin Complete basis set calculations at the MP2 and CCSD(T) levels. J. Phys. Chem. A 109, 1131-1136 (2005)... 

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