Diffraction results

PM3/TM is an extension of the PM3 method to include d orbitals for use with transition metals. Unlike the case with many other semiempirical methods, PM3/TM s parameterization is based solely on reproducing geometries from X-ray diffraction results. Results with PM3/TM can be either reasonable or not depending on the coordination of the metal center. Certain transition metals tend to prefer a specific hybridization for which it works well. 

Maleic and fiimaric acids have physical properties that differ due to the cis and trans configurations about the double bond. Aqueous dissociation constants and solubiUties of the two acids show variations attributable to geometric isomer effects. X-ray diffraction results for maleic acid (16) reveal an intramolecular hydrogen bond that accounts for both the ease of removal of the first carboxyl proton and the smaller dissociation constant for maleic acid compared to fumaric acid. Maleic acid isomerizes to fumaric acid with a derived heat of isomerization of —22.7 kJ/mol (—5.43 kcal/mol) (10). The activation energy for the conversion of maleic to fumaric acid is 66.1 kJ/mol (15.8 kcal/mol) (24). 

Section 4.04.1.2.1). The spectroscopic and the diffraction results refer to molecules in different vibrational quantum states. In neither case are the- distances those of the hypothetical minimum of the potential function (the optimized geometry). Nevertheless, the experimental evidence appears to be strong enough to lead to the conclusion that the electron redistribution, which takes place upon transfer of a molecule from the gas phase to the crystalline phase, results in experimentally observable changes in bond lengths. 

Table 1 Comparison of MD and X-Ray Diffraction Results for Structural Parameters of Fully Hydrated DPPC Bilayers...

Table 2. X-Ray diffraction results and degree of graphitization of various carbon fibers.

Here are the results from this job using the two different basis sets. We also include experimental electron diffraction results ... 

The reflection 7 of x-rays by a crystal (x-ray diffraction) results fundamentally from the unmodified scattering of x-rays by the atoms or ions in the different planes of the crystal. For many purposes, it suffices to regard the atoms or ions as the scattering centers, but a complete description of the process requires that the electrons be considered. 

The Li-Zn phase diagram shows the presence of eight intermediate phases. Later x-ray diffraction results confirm the existence of five intermediate RT phases " . Polymorphism is shown by the three compounds shown in the Li-Cd phase system, and this has confused the interpretation of x-ray diffraction patterns ". 

Nanocrystals titania was prepared by sol-gel method. X-ray diffraction result is shown in Figure 1, all samples were anatase phase. Based on Sherrer s equation, these samples had crystallite sizes about 7 nm. From XRD results, it indicated that titania samples showed the similar of crystallinity because the same ordering in the structure of titania particles make the same intensity of XRD peaks. 

We wish to thank Dr. Raymond G. Teller for the x-ray and neutron diffraction results and Prof. Edward Kostlner for fruitful discussions. 

Determined by electron diffraction results from Hargittai, Ref. 5, p. 80. 

These results are consistent with XRD (X-ray diffraction) results. The amounts of K-feldspar, K-mica and chlorite are higher in the altered rocks closer to the veins and Ca-zeolites and smectite decrease in amounts towards periphery of the alteration zones. 

The Pn conformation of poly-L-proline (PP) or collagen in the solid state could be identified from X-ray fiber diffraction results (Cowan and McGavin, 1955). Persistence of this basic structure in solution was inferred from the resemblance between the CD spectra of solutions and films of the polypeptide. The CD spectra of the charged forms of PGA and PL closely resemble that of Pn (compare Fig. IB, 1C, and ID) however, these spectra differ significantly from those of PP peptides at high temperature or in the presence of high concentration of salts... 

As an example, Cooper and coworkers have used polarized ATR spectroscopy to characterize the surface orientation of PET bottles [35]. They first confirmed the quantitative agreement between ATR and X-ray diffraction results, and then studied the molecular orientation of the bottles at 2 cm intervals. 

The X-ray diffraction results showed that peaks of calcite disappeared after extraction of the carbonate (CARB) fraction by the NaOAc-HOAc solution at pH 5.0 from the soils with 10-30% of CaC03, such as soils H13, B10 and J3. This indicates that the buffer solution at pH 5.0 is able to... 

Fig. 12 400° C section of the Sc-Mg-Zn phase distribution according to power diffraction results, roughly outlining the phase regions of the 1/1 AC, 2/1 AC and Tsai-type i-QC...

Several of the species contain a semi-br idging CO ligand for which there is either i.r. (v circa 1 850 cm-1) or X-ray evidence. An interesting feature of the structure oT (10) is that the X-ray diffraction results reveal the presence of an n2-C = 0 Bridging group. A similar ligand is probably present in (1J) since both (10) and (]J) show CO stretching bands in the i.r. at 1 638 and 1 578 cm-, respectively, as well as terminal CO bands at 1 930 and 1 937 cm" . 

Hijas et al. (87) concluded from their neutron diffraction results that Ti is distributed among only four or five of the 12 sites, with Ti occupying T3(0.30),... 

More recent quantum-based MD simulations were performed at temperatures up to 2000 K and pressures up to 30 GPa.73,74 Under these conditions, it was found that the molecular ions H30+ and OH are the major charge carriers in a fluid phase, in contrast to the bcc crystal predicted for the superionic phase. The fluid high-pressure phase has been confirmed by X-ray diffraction results of water melting at ca. 1000 K and up to 40 GPa of pressure.66,75,76 In addition, extrapolations of the proton diffusion constant of ice into the superionic region were found to be far lower than a commonly used criterion for superionic phases of 10 4cm2/s.77 A great need exists for additional work to resolve the apparently conflicting data. 

An ethanol-condensed aggregate manifests FPA relaxation and X-ray diffraction results similar to those obtained for the viruses with nonglucosylated DNAs, albeit with even more restricted motion.(57) The interhelix spacing in the ethanol-induced aggregate was similar to that of the X, XA, and T4dC DNAs (2.7 nm), but shorter than that in spermidine-induced aggregates (3.0nm), which showed relatively normal torsional dynamics.(57)... 

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