Pub Date : 1987-09-15DOI: 10.1107/S0108270187090048
D. Schwarzenbach, J. Daly, A. Pinkerton
{"title":"Structure of Isoquinolinium Nitrate and a Redetermination of the Corresponding Chloride","authors":"D. Schwarzenbach, J. Daly, A. Pinkerton","doi":"10.1107/S0108270187090048","DOIUrl":"https://doi.org/10.1107/S0108270187090048","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"45 1","pages":"1818-1821"},"PeriodicalIF":0.0,"publicationDate":"1987-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90962531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-08-12DOI: 10.1107/S0108767387077766
D. Schwarzenbach, H. Flack
{"title":"Origin-Defining Restraints in Polar Space Groups","authors":"D. Schwarzenbach, H. Flack","doi":"10.1107/S0108767387077766","DOIUrl":"https://doi.org/10.1107/S0108767387077766","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1987-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78446273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-08-12DOI: 10.1107/S0108767387077948
D. Schwarzenbach
{"title":"Report on the Work of the Subcommittee on Statistical Descriptors","authors":"D. Schwarzenbach","doi":"10.1107/S0108767387077948","DOIUrl":"https://doi.org/10.1107/S0108767387077948","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1987-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90919612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-03-01DOI: 10.1107/S0108767387099525
D. Schwarzenbach, J. Didisheim
The rigid-bond condition for harmonic thermal parameters states that the difference of the mean-square displacements of atoms A and B along the covalent bond A-B is negligible. In this paper, the corresponding condition for non-bonded intramolecular distances is called a rigid link. Rigid-body motion according to the TLS formalism requires all intramolecular links to be rigid. Conversely, a cornpiece set of rigid links is not necessarily equivalent to rigid-body motion. An algorithm is presented for the determination of the maximum number QN of independent rigid links of an N-atom molecule. In general for site symmetry 1, QN = N-1 for linear and 3N-6 for planar molecules. For three-dimensional molecules, QN = N(N - 1)/2, N ≤ 8 and 6N-20, N ≥ 8. For particular geometries, QN may be smaller. For many molecules, QN rigid links are equivalent to rigid-body motion. Notable exceptions are most linear and planar molecules, and all molecules with six or seven atoms. Higher site symmetries reduce and often eliminate these differences between rigid links and rigid-body motion. The use of rigid-link restraints in crystallographic least squares is recommended. They provide a computationally simple means of relaxing the constraints imposed on the displacement parameters by the TLS model for any molecular site symmetry.
{"title":"Rigid-Link Constraints and Rigid-Body Molecules","authors":"D. Schwarzenbach, J. Didisheim","doi":"10.1107/S0108767387099525","DOIUrl":"https://doi.org/10.1107/S0108767387099525","url":null,"abstract":"The rigid-bond condition for harmonic thermal parameters states that the difference of the mean-square displacements of atoms A and B along the covalent bond A-B is negligible. In this paper, the corresponding condition for non-bonded intramolecular distances is called a rigid link. Rigid-body motion according to the TLS formalism requires all intramolecular links to be rigid. Conversely, a cornpiece set of rigid links is not necessarily equivalent to rigid-body motion. An algorithm is presented for the determination of the maximum number QN of independent rigid links of an N-atom molecule. In general for site symmetry 1, QN = N-1 for linear and 3N-6 for planar molecules. For three-dimensional molecules, QN = N(N - 1)/2, N ≤ 8 and 6N-20, N ≥ 8. For particular geometries, QN may be smaller. For many molecules, QN rigid links are equivalent to rigid-body motion. Notable exceptions are most linear and planar molecules, and all molecules with six or seven atoms. Higher site symmetries reduce and often eliminate these differences between rigid links and rigid-body motion. The use of rigid-link restraints in crystallographic least squares is recommended. They provide a computationally simple means of relaxing the constraints imposed on the displacement parameters by the TLS model for any molecular site symmetry.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"68 1","pages":"226-232"},"PeriodicalIF":0.0,"publicationDate":"1987-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77198257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1986-08-15DOI: 10.1107/S0108270186093411
K. Schenk, G. Chapuis
Cristallisation dans le systeme monoclinique, groupe P2 1 et affinement jusqu'a R=0,032. Le caractere amphiphile de l'ion provoque la cristallisation en couches
单斜体系结晶，P2 1组，精炼至R= 0.032。离子的双亲性导致层状结晶
{"title":"Room Temperature Phase of n-Decylammonium Chloride","authors":"K. Schenk, G. Chapuis","doi":"10.1107/S0108270186093411","DOIUrl":"https://doi.org/10.1107/S0108270186093411","url":null,"abstract":"Cristallisation dans le systeme monoclinique, groupe P2 1 et affinement jusqu'a R=0,032. Le caractere amphiphile de l'ion provoque la cristallisation en couches","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"41 1","pages":"1076-1078"},"PeriodicalIF":0.0,"publicationDate":"1986-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86823114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-05-01DOI: 10.1107/S0108767385000575
G. Chapuis, D. H. Templeton, L. K. Templeton
The anomalous scattering terms for trivalent holmium are measured for Cu Kα1, Kα2 and Kβ radiation in diffraction experiments with a crystal of HoNa(edta).8H2O. Intensities at these wavelengths and at Mo Kα are used to calculate amplitudes and the phase difference for the waves scattered by holmium and by the rest of the structure to test the multiple-wavelength method of diffraction phase determination. Relative phases are determined with a mean accuracy of 44° for 759 high-angle reflections. A similar calculation for the analogous Sm crystal using synchrotron radiation data gives the phase difference with an average error of 5°.
{"title":"Solving Crystal Structures Using Several Wavelengths from Conventional Sources. Anomalous Scattering by Holmium","authors":"G. Chapuis, D. H. Templeton, L. K. Templeton","doi":"10.1107/S0108767385000575","DOIUrl":"https://doi.org/10.1107/S0108767385000575","url":null,"abstract":"The anomalous scattering terms for trivalent holmium are measured for Cu Kα1, Kα2 and Kβ radiation in diffraction experiments with a crystal of HoNa(edta).8H2O. Intensities at these wavelengths and at Mo Kα are used to calculate amplitudes and the phase difference for the waves scattered by holmium and by the rest of the structure to test the multiple-wavelength method of diffraction phase determination. Relative phases are determined with a mean accuracy of 44° for 759 high-angle reflections. A similar calculation for the analogous Sm crystal using synchrotron radiation data gives the phase difference with an average error of 5°.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"16 1","pages":"274-278"},"PeriodicalIF":0.0,"publicationDate":"1985-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79647458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1984-08-09DOI: 10.1080/00268948408071676
G. Chapuis, K. Schenk
Abstract Different types of n-alkyl containing compounds have been studied by temperature controlled single crystal x-ray diffraction. They crystallize in layers of alkylammonium ions alternating with layers of counter ions. The organic layers mimic liquid crystals of the smectic type or bilayers as found in biomembranes. These compounds exhibit numerous phase transitions which are due mainly to different chain conformations. In one example, the transitions preceding the melting of the chains has been analysed step by step and shows the evolution of the various chain conformations. In another example, evidence has been found of the separation of the chains from an intercalated type of packing to a non-intercalated type.
{"title":"Temperature induced phase transitions in lipid bilayer models","authors":"G. Chapuis, K. Schenk","doi":"10.1080/00268948408071676","DOIUrl":"https://doi.org/10.1080/00268948408071676","url":null,"abstract":"Abstract Different types of n-alkyl containing compounds have been studied by temperature controlled single crystal x-ray diffraction. They crystallize in layers of alkylammonium ions alternating with layers of counter ions. The organic layers mimic liquid crystals of the smectic type or bilayers as found in biomembranes. These compounds exhibit numerous phase transitions which are due mainly to different chain conformations. In one example, the transitions preceding the melting of the chains has been analysed step by step and shows the evolution of the various chain conformations. In another example, evidence has been found of the separation of the chains from an intercalated type of packing to a non-intercalated type.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1984-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90065925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1984-08-09DOI: 10.1107/S0108767384095155
R. Restori, D. Schwarzenbach
{"title":"Electron Density Distribution of Rutile, TiO2","authors":"R. Restori, D. Schwarzenbach","doi":"10.1107/S0108767384095155","DOIUrl":"https://doi.org/10.1107/S0108767384095155","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1984-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83518905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1981-08-16DOI: 10.1107/S0108767381096499
K. Schenk, G. Chapuis
{"title":"Phase transitions in n-decylammoniumchloride","authors":"K. Schenk, G. Chapuis","doi":"10.1107/S0108767381096499","DOIUrl":"https://doi.org/10.1107/S0108767381096499","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1981-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77564699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1981-08-16DOI: 10.1107/S0108767381088910
A. Pinkerton, S. Spiliadis, D. Schwarzenbach, A. Söderholm
{"title":"The structure of dithiophosphinate complexes of the lanthanides in the solid and in solution (X-ray + NMR)","authors":"A. Pinkerton, S. Spiliadis, D. Schwarzenbach, A. Söderholm","doi":"10.1107/S0108767381088910","DOIUrl":"https://doi.org/10.1107/S0108767381088910","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1981-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86851545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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