Statistics of derived intensities

McCandlish, L. E.; Stout, George H.; Andrews, Larry C.

doi:10.1107/s0567739475000496

Cited by 198 publications

(94 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Intensity data were corrected for Lorentz and polarization effects, the scale variation and for absorption (Gaussian integration [11]). The variance a2(I) was calculated on the basis of counting statistics plus the term (pi)2, where P is the instability constant [12] as derived from the excess variance in the reference reflections. Inspection of the data sets showed the Laue symmetry to be 6/mmm; the 00 l reflections with l odd are systematically extinct, which indicates the space group to be P6322.…”

Section: Structure Determinationmentioning

confidence: 99%

Crystal structure and band structure calculations of and

Fang

Wiegers

Meetsma

et al. 1996

Physica B: Condensed Matter

View full text Add to dashboard Cite

Crystal structure and band structure calculations of Pb1/3TaS2 and Sn1/3NbS2 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Fang, C. M., Wiegers, G. A., Meetsma, A., de Groot, R. A., & Haas, C. (1996). Crystal structure and band structure calculations of Pb1/3TaS2 and Sn1/3NbS2. Physica B, 226(4), 259 -267. DOI: 10.1016/0921-4526(96)00271-2 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractThe crystal structures of Pb~/3TaS2 and Sn~/3NbS2 were determined using single-crystal X-ray diffraction. The space group is P6322 and the unit cell dimensions are: a = 5.759(1 ), c = 14.813(1)A and a = 5.778(1), c = 14.394(1 )/~, for the Pb and Sn compounds, respectively. The post-transition metal atoms occupy one-third of the trigonal-antiprismatic holes between sandwiches NbS2 and TaS2. The Nb and Ta atoms are in trigonal-prismatic coordination by sulfur atoms. The stacking of sandwiches is the same as in 2H disulfides. The arrangement of the post-transition metal atoms is different for the two compounds. A bond valence calculation showed Sn and Pb to be divalent.Ab initio band structure calculations were performed for Snl/3NbS2 using the localized spherical wave method, and for Pbl/3TaS2 with the augmented spherical wave method with spin-orbital interactions included. The calculations show that the rigid band model is approximately valid for the electronic structures; the main difference with those of 2H-NbS2 and 2H-TaS2 being the presence of Sn 5s and 5p (Pb 6s and 6p) bands and a larger S 3p/Nb(Ta) 4d (5d) gap in the intercalates (l.0eV for Snl/3NbS2, 1.3 eV for Pbl/3TaS2). The Sn 5s (Pb 6s) bands are at the bottom (bonding) and top (antibonding) of the valence bands which range from about -7 to about 0 eV. The conduction bands are composed of Nb 4d:2 or Ta 5d~2 orbitals hybridized with S 3p. These bands are filled to about 0.3 holes per Nb (Ta), corresponding to a donation of two electrons per Sn (Pb). I. IntroductionDiSalvo et al. [1] were the first to study the compounds MxTaS2 with M a post-transition element (Ga, In, Ge, Sn, Pb); they used X-ray powder methods for characterization. Eppinga and Wiegers [2] synthesized, besides the compounds already found by DiSalvo et al.

show abstract

Section: Structure Determinationmentioning

confidence: 99%

Crystal structure and band structure calculations of and

Fang

Wiegers

Meetsma

et al. 1996

Physica B: Condensed Matter

View full text Add to dashboard Cite

show abstract

“…Intensities were corrected for Lorentz and polarization effects, not for absorption. Variance o2(1) was calculated based on counting statistics plus a term (pl)2 where P(=0.013) is the instability constant (McCandlish, Stout & Andrews, 1975). The structure was solved by direct methods using MULTAN80 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1980) and refined on …”

Section: By Pieter F W Stouten Paul Verwer Bouke P Van Eijck Andmentioning

confidence: 99%

Conformational aspects of meso-tartaric acid. XI. Structure of lithium hydrogen meso-tartrate monohydrate

Stouten¹,

Verwer²,

Eijck³

et al. 1988

Acta Crystallogr C

View full text Add to dashboard Cite

oxygen atoms 02 and 03 respectively (Table 2d). This is in contrast to the structure of arginyl-glutamic acid which shows specific H-bonding interactions between the guanidyl group and carboxyl oxygen atoms of the glutamic acid side chain (Pandit, Seshadri & Viswamitra, 1983). Fig. 2 and Table 2(d) show that the two water molecules in the asymmetric unit form independent water chains along b. These chains are also H-bonded to the L-arginyl-L-aspartic acid residues.We thank Dr T. P. Seshadri for his help during data collection and DST and DBT for financial support.References Enraf-Nonius (1979 (2), c = 5.3107 (4)A, fl=95.768 (5) °, V= 654.71 (7) A 3, Z =4, Dx=l.766gcm -3, 2(MoKa)=0.71073A, g =1.6cm -x, F(000)=360, T=294K, R=0.042, wR=0.048 for 2326 observed reflections with I > 2.5tr(I). The crystal structure is a racemate of two conformational antipodes of the meso-tartrate anion, which has adopted its usual gauche conformation with respect to the carbon chain. The glycolic acid parts are almost planar. The Li ÷ ion is irregularly coordinated to five O atoms at a mean distance of 2.05 (6) tl,.Introduction. The crystal structure determination of the title compound is part of the research program which is being carried out on the molecular conformational aspects of neutral meso-tartaric acid and its ionized forms. A second point of interest is the nature of hydr0gen-bond schemes inacid salts in general.

show abstract

“…The intensity data were corrected for Lorentz and polarization effects and scale variation, but an absorption correction was judged not to be necessary in view of the small observed variation in intensity of a 360 o ~b scan of a close-to-axial reflection (202). The variance tr 2 (/) was calculated on the basis of counting statistics plus the term (P1) 2, where P (--0.021) is the instability constant as derived from the excess variance in the reference reflections (McCandlish, Stout & Andrews, 1975). Equivalent reflections were averaged and stated observed if satisfying the criterion I > 2.5cr(/).…”

mentioning

confidence: 99%