Anisotropic temperature factors and screw rotation coefficients from a lattice dynamical viewpoint

1968 ◽  
Vol 24 (4) ◽  
pp. 485-486 ◽  
Author(s):  
G. S. Pawley
Keyword(s):  
Anisotropic Temperature ◽  
Temperature Factors

Crystal structure of KCaF3 determined by the Rietveld profile method

1997 ◽  
Vol 12 (2) ◽  
pp. 70-75 ◽  
Author(s):  
Alicja Ratuszna ◽  
Michel Rousseau ◽  
Philippe Daniel
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Lattice Parameters ◽  
Profile Method ◽  
Anisotropic Temperature ◽  
Monoclinic Distortion ◽  
Refinement Procedure ◽  
Watson Statistic ◽  
Temperature Factors ◽  
Atomic Coordinates

Using the Rietveld profile method, the atomic coordinates and anisotropic temperature factors of KCaF3 were refined. At room temperature, KCaF3 crystallizes in monoclinic B21/m symmetry, with the lattice parameters: a=8.754(2) Å, b=8.765(4) Å, c=8.760(5) Å, β=90.48(3)°, V=672.1(3) Å3, Z=8. The refinement procedure was stopped when RB=0.05 and the Durbin–Watson statistic factor=0.85 had been reached. The structure determined is related to the tilting of CaF6 octahedra of the a−b+c− type, which are responsible for the monoclinic distortion in perovskite crystals.

scholarly journals A new Rubidium - Bismuth polyphosphate RbBi(PO3)4: Growth, X-ray single crystal and vibrational study

2014 ◽  
Vol 10 (7) ◽  
pp. 2881-2893
Author(s):  
Khaled JAOUADI ◽  
Tahar MHIRI ◽  
Nabil ZOUARI
Keyword(s):  
Single Crystal ◽  
Structural Type ◽  
Inorganic Materials ◽  
X Ray ◽  
Weighted Residuals ◽  
Type Iv ◽  
Anisotropic Temperature ◽  
Solution Studies ◽  
Bridge Oxygen ◽  
Temperature Factors

Solid-solution studies in the ternary Rb2O – Bi2O3 – P2O5 system, carried out in a search for inorganic materials have a considerable interest mainly for their optical properties, specifically in laser technology, yielded the new compound RbBi(PO3)4. Single-crystal X-ray measurement revealed that RbBi(PO3)4 crystallizes in space group P21/c with a structural type IV and has lattice parameters a = 10.430, b = 8.984, c = 12.967 Å,  = 126.1°, Z = 4 and V = 981.6 Å3. The all eighteen atoms were located in the asymmetric unit. Refinement using anisotropic temperature factors for all atoms yielded weighted residuals based on F and F2 values, respectively, of R1 = 0.0131 and WR2 = 0.0252 for all observed reflections. The atomic arrangement can be described as a long chain polyphosphate organization, helical ribbons (PO3)n. Two types of infinite chains, with a period of eight PO4 tetrahedra run along the longest unit-cell directions. Infrared and Raman spectra at room temperature, were investigated, show clearly some characteristics bands of infinite chains structure of PO4 tetrahedra linked by a bridge oxygen.

The crystal structure of diamminesilver dinitroargentate, [Ag(NH3)2]Ag(NO2)2*

1977 ◽  
Vol 146 (4-6) ◽  
Author(s):  
H. M. Maurer ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Heavy Atom ◽  
Anisotropic Temperature ◽  
Light Atoms ◽  
Difference Fourier ◽  
Temperature Factors ◽  
Heavy Atom Method ◽  
Silver Atoms ◽  
Block Diagonal

AbstractThe crystal structure of diamminesilver dinitroargentate, [Ag(NHThe point positions of the silver atoms were obtained by the heavy-atom method whereas those of the light atoms were found by difference Fourier syntheses. Coordinates and anisotropic temperature factors were refined by block-diagonal least-squares methods with the result

A REFINEMENT OF THE CRYSTAL STRUCTURES OF (NH4)2TeBr6 AND Cs2TeBr6

1966 ◽  
Vol 44 (8) ◽  
pp. 939-943 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Bromine Atom ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Temperature Factors

(NH4)2TeBr6 and Cs2TeBr6 crystals have the cubic K2PtCl6 structure with space group: [Formula: see text] with a0 = 10.728 ± 0.003 Å and 10.918 ± 0.002 Å respectively. The positional coordinate of the bromine atom, and the anisotropic temperature factors of all atoms in the unit cell, have been refined for both crystals by a full matrix least-squares analysis of the three dimensional X-ray diffraction data (R = 0.08). The Te—Br distance, corrected for probable thermal motions of atoms forming the bond, is 2.70 ± 0.01 Å in both crystals.

Three-dimensional refinement of the structure of β-succinic acid

1959 ◽  
Vol 251 (1267) ◽  
pp. 441-457 ◽  
Keyword(s):  
Succinic Acid ◽  
Three Dimensional ◽  
Molecular Crystals ◽  
Carboxyl Group ◽  
Single Bond ◽  
Fourier Methods ◽  
Angular Oscillation ◽  
Anisotropic Temperature ◽  
Temperature Factors ◽  
Van Der Waals Contacts

The crystal structure of β-succinic acid has been refined by three-dimensional Fourier methods, followed by differential refinements with series-termination corrections and anisotropic temperature factors. The central C—C bond at 1·533 Å is shown not to differ significantly from the length of the single bond in diamond, but the next bond connecting the chain to the carboxyl group, C—COOH, is 1·485 ± 0·013 Å and the contraction here is highly significant. The C—O distances are 1·252 and 1·322 Å, with standard deviations of about 0·012 Å. The main feature of the thermal motion is that the movement in the direction of the hydrogen-bonded molecular columns is very much less than in any other direction in the crystal, and also much less than in pure molecular crystals like benzene or naphthalene. In other directions where van der Waals contacts only exist the movement is greater. There is a molecular angular oscillation of perhaps 9° r.m.s. amplitude about an axis close to the axis of the molecular columns. A difference synthesis in the plane of the oxygen atoms is given which shows the hydrogen atom responsible for hydrogen bonding.

scholarly journals Satellite tobacco mosaic virusrefined to 1.4 Å resolution

2014 ◽  
Vol 70 (9) ◽  
pp. 2316-2330 ◽  
Author(s):  
Steven B. Larson ◽  
John S. Day ◽  
Alexander McPherson
Keyword(s):  
Icosahedral Symmetry ◽  
Structural Detail ◽  
Virus Structure ◽  
Density Maps ◽  
Satellite Tobacco Mosaic Virus ◽  
Anisotropic Temperature ◽  
First Time ◽  
Temperature Factors ◽  
Precise Assessment ◽  
Resolution Data

Satellite tobacco mosaic virus(STMV) is among the smallest viruses, having 60 identical subunits arranged withT= 1 icosahedral symmetry. Its crystal structure was solved at 290 K and was refined using, in part, crystals grown in microgravity. Electron-density maps revealed nearly 57% of the genomic ssRNA. Using six flash-cooled crystals, diffraction data were recorded to 1.4 Å resolution and independent refinements of the STMV model were carried outversusthe previous 1.8 Å resolution data representing merged data from 21 crystals (271 689 unique reflections), data consisting of corresponding reflections to 1.8 Å resolution from the cooled crystals and 1.4 Å resolution data from the cooled crystals comprised of 570 721 unique reflections. Models were independently refined with full NCS constraints using the programCNSand in restrained mode using the programsCNS,REFMAC5 andSHELX-97, with the latter two procedures including anisotropic temperature factors. Significant additional structural detail emerged from the analyses, including a unique cation and anion arrangement on fivefold axes and a precise assessment of icosahedral symmetry exactness in the crystal lattice. STMV represents the highest resolution native virus structure currently known by a substantial margin, and it permits the evaluation of a precise atomic model of a spherical virus at near-atomic resolution for the first time.

The crystal and electron structure of O-(2-chloroethyl)-O-isobutyl-O-(2-phenyl-4-methylthio-3-oxo-2H-pyridazine-5-yl) thiophosphate

1987 ◽  
Vol 52 (3) ◽  
pp. 696-706 ◽  
Author(s):  
Viktor Vrábel ◽  
František Pavelčík ◽  
Eleonóra Kellö ◽  
Stanislav Miertuš ◽  
Václav Konečný ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
Bond Distance ◽  
Direct Methods ◽  
Electron Structure ◽  
Anisotropic Temperature ◽  
Wiberg Index ◽  
Trigonal Pyramid ◽  
Net Charges ◽  
Temperature Factors

The crystal structure of the title fungicide was solved by direct methods, using Σ2 relationship and tangent formula. The structure refinement was made by full-matrix least-squares with anisotropic temperature factors to the final R = 0.096 for 1 486 significant reflexions. The compound crystallizes in the orthorhombic system, the space group Pccn. The lattice parameters are a = 1.8719(9), b = 3.0426(33), c = 0.7616(2) nm and Z = 8. The intermolecular interactions of types C-H···Cl and C-H···O are observed between the centrosymmetrically related molecules in the crystal structure. The coordination polyhedron around phosphorus is between trigonal pyramid and tetrahedron. The planes of the phenyl and pyridazine rings are rotated through 70° each other. The electron structure was calculated by semiempirical CNDO/2 method. The calculations revealed the most negative net charges on S(2) and O(1). The value of Wiberg index Iw = 1.08 and the bond distance 0.149 nm show that the bond N(1)-C(5) is simple and is not involved in the conjugation.

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