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Structure deformed crystal

The electronic structures of poiy(fluoroacetylene) and poly(difluoroacetylene) have been investigated previously using the ab initio Hartree-Fock crystal orbital method with a minimum basis set (42). Only the cis and trans isomers with assumed, planar geometries were studied. The trans isomer was calculated to be more stable in both cases, and the trans compounds were predicted to be better intrinsic semiconductors and more conductive upon reductive doping than trans polyacetylene. However, our results show that head-to-tail poly(fluoroacetylene) prefers the cis structure and that the trans structure for poly(difluoroacetylene) will not be stable. Thus the conclusions reached previously need to be re-evaluated based on our new structural information. Furthermore, as noted above, addition of electrons to these polymers may lead to structural deformations that could significantly change the conductive nature of the materials. [Pg.32]

Friedman PS, Kopelman R, Prasad PN (1974) Spectroscopic evidence for a continuous change in molecular and crystal structure Deformation rfbiphenyl in the low temperature solid. Chem. Phys. Lett. 24 15... [Pg.116]

Excimer emission is observed from many crystals when they are subjected to pressure or when they are strongly deformed in some other manner. In the deformed crystals, molecular configurations are produced which favour excimer emission. Through annealing, these defects can often be removed again. Also in vapour-deposited films which are initially amorphous at low temperatures, excimer structures can frequently be formed by a suitable annealing process. [Pg.156]

The slip occurs when the crystal is subjected to a stress, and the dislocation moves through the crystal until it reaches the edge or is arrested by another dislocation, as shown in Figure 9. Position 1 shows a normal crystal structure. Position 2 shows a force applied from the left side and a counterforce applied from the right side. Positions 3 to 5 show how the structure is slipping. Position 6 shows the final deformed crystal structure. The slip of one active plane is ordinarily on the order of 1000 atomic distances and, to produce yielding, slip on many planes is required. [Pg.38]

Mechanical deformation, crystallization of the complex in the presence of electrical field, and gradual directional evaporation of the solution of PC with CT complex have been tested as methods to obtain structural modifications of the conductive crystalline network. [Pg.173]

The tephra layers exposed on the ice fields west of the AUan HiUs were mapped by Dunbar (1995a, b) who also attanpted to date anorthoclase crystals contained within them by the Ar/ Ar method. The outcrop patterns of these tephra layers in Fig. 17.48 demonstrate their linear continuity and the structural deformation of the ice in this area. The same investigators also sampled dnst layers on other ice fields associated with the AUan HiUs, such as the ice around the Elephant and Redding moraines, the Ear Western, Ear Northern, and Meteorite City ice fields, ice adjacent to Carapace Nunatak, and other localities on the margin of the East Antarctic ice sheet in southern Victoria Land. [Pg.621]

In eq. (92) ExJJ ) is the energy of the elastic-deformed crystal involving the corresponding contributions of the electronic subsystem, which retains the structure of eq. (20), though with renormalized matrices of coefficients ... [Pg.334]

ELECTRONIC DENSITY BY STRUCTURE FACTOR FOR DEFORMED CRYSTALS... [Pg.581]

Putz, M. V. (2003). Electronic Density from Structure Factor Determination in Small Deformed Crystals./nf.J. QuantumChem. 94(4),222-231 (DOI 10.1002/qua.l0475). Birau, O., Putz, M. V. (2000). The Standing Waves Concept in Dynamical Theory of X-Ray Diffraction (in Romanian), Mirton Publishing House, Timisoara, Chapter 5. [Pg.618]


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See also in sourсe #XX -- [ Pg.14 ]




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Deformation structure

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