Full-matrix least-squares refinement

Full-matrix least-squares refinement of the structure model was carried out with programs orfls (9). Since this program in the form we used refines structure factors Fhki rather than the intensities of the powder lines, it was necessary to decompose the intensity of each line having more than one component into contributions from the individual component reflections. This was done by assuming that the F°mz 2 for the several components of a powder line were in the same ratios as the corresponding FcftfcZ 2 obtained from a structure model—the original trial structure or the previous... 

Partially Dehydrated Ba6 A. Full-matrix least-squares refinement was initiated using the atomic parameters of the framework atoms and of the barium ions (Ba(l), Ba(2), Ba(3), and Ba(4)) in fully hydrated Ba2+-exchanged zeolite A. Full anisotropic refinement converged to the error indices = 0.113 and R2 = 0.088. Simultaneously, the occupancy numbers at Ba(l),... 

Suitable small crystals of 2XeF,AsF, were obtained by sublimation under nitrogen (at atmos.) in sealed quartz AT-ray capillaries. A tablet measuring <01 mm. in any dimension was used for the intensity data. The crystals are monoclinic with unit-cell dimensions a = 16-443, b = 8-678, c = 20-888 A, )S = 90-13°, V = 2799 A -The space group is 12/a, and Z 12 Three-dimensional data, amounting to 1182 non-zero independent reflections, were obtained. Two xenon and one arsenic atoms were located with a three-dimensional Patterson map, and the remaining atomic p>ositions from subsequent electron-density maps. Full-matrix least-squares refinement led to a final conventional R-value of 0-066. 

Structural Solution and Refin ent. The structure was solved by analysis of similar structuies and expanded using Fourier maps. All atoms were refined anisotropically. The final cycle of full-matrix least-squares refinement was based on 555 observed reflections (7 > 3.00o(7)) and 70 variable parameters and converged (largest parameter shift was 0.00 times its esd) with unweighted and weighted agreement foctors of... 

The structure was solved by heavy-atom methods at the U.C. Berkeley CHEXRaY facility using full-matrix least-squares refinement procedures detailed elsewhere. Systematically absent reflections were eliminated from the data set, and those remaining were corrected for absorption by means of the calculated absorption coefficient. A three-dimensional Patterson synthesis gave peaks that were consistent with Xe atoms in Wyckoff position 4c and Ge atoms in 4a in space group Pnmb (see Pnma, No. 62). Three cycles of... 

Full-matrix least-squares refinement was begun using the atomic parameters of the framework atoms [(Si,Al), 0(1), 0(2), and 0(3)]... 

V=4629.5(7) A, Z=2, Dc=4.108 g cm , [x=237.58 cm The structure was solved by direct methods (MULTAN 88) and refined using a full-matrix least-squares refinement procedure 19552 unique reflections (Rint=0.077), 10246 observed reflections with />3a(/), J =0.067, R ,=0.078, 680 refined parameters, and 20max=55°. Lorentz polarization and absorption correction (ABSCQR) were applied to the intensity data. The transmission... 

Run 20 cycles of full matrix least squares refinement Refine only coordinates Use data between 10 and 2.0 A Begin refinement with data to 4.0 A, then with every cycle include successive 0.3 A shells of data... 

SMART programs. All non-hydrogen atoms were refined on anisotropicaUy by full-matrix least squares method. Hydrogen atoms were observed and refined with a fixed isotropic displacement parameter. Full-matrix least-squares refinement gave final values of R = 0.039 and Rw = 0.109. The max and min difference between peaks and holes was 330 and -280 e nm, respectively. 

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