Pub Date : 2020-12-21DOI: 10.1107/s1574870720003274
J. Kas, F. Vila, J. Rehr
{"title":"The FEFF code","authors":"J. Kas, F. Vila, J. Rehr","doi":"10.1107/s1574870720003274","DOIUrl":"https://doi.org/10.1107/s1574870720003274","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"32 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132812298","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 : 2020-12-21DOI: 10.1107/s1574870720003420
M. Benfatto, G. Chillemi, E. Pace
X-ray absorption near-edge structure (XANES) spectroscopy is a powerful method for obtaining local structural and electronic information around a well defined absorbing site of matter in many possible different conditions. The MXAN method allows a complete fit of the XANES energy region in terms of a well defined set of structural parameters. This approach is based on the comparison between experimental data and many theoretical calculations performed by varying selected structural parameters starting from a putative structure, i.e. from a well defined initial geometrical configuration around the absorber. The X-ray photoabsorption cross sections are derived using full multiple-scattering theory, i.e. the scattering path operator is calculated exactly without any series expansion. In this way, the analysis can start from the edge without any limitations in the energy range and polarization conditions. In this chapter, details of MXAN are presented with some new improvements that allow the analysis of time-dependent XANES data and structurally disordered systems.
{"title":"MXAN: a method for the quantitative structural analysis of the XANES energy region","authors":"M. Benfatto, G. Chillemi, E. Pace","doi":"10.1107/s1574870720003420","DOIUrl":"https://doi.org/10.1107/s1574870720003420","url":null,"abstract":"X-ray absorption near-edge structure (XANES) spectroscopy is a powerful method for obtaining local structural and electronic information around a well defined absorbing site of matter in many possible different conditions. The MXAN method allows a complete fit of the XANES energy region in terms of a well defined set of structural parameters. This approach is based on the comparison between experimental data and many theoretical calculations performed by varying selected structural parameters starting from a putative structure, i.e. from a well defined initial geometrical configuration around the absorber. The X-ray photoabsorption cross sections are derived using full multiple-scattering theory, i.e. the scattering path operator is calculated exactly without any series expansion. In this way, the analysis can start from the edge without any limitations in the energy range and polarization conditions. In this chapter, details of MXAN are presented with some new improvements that allow the analysis of time-dependent XANES data and structurally disordered systems.","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131692253","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 : 2020-12-21DOI: 10.1107/s1574870720003171
P. Blaha
WIEN2k is a versatile and user-friendly code for calculating the electronic structure of solids. It is based on density-functional theory (DFT) and can use a wide variety of different functionals. It utilizes the augmented plane-wave method and treats all electrons (core and valence) self-consistently, making it a very accurate method. It calculates the basic electronic structure, allows structure optimization and can simulate various spectroscopies. For X-ray absorption or electron energy-loss spectroscopy, excitonic effects can be considered using a core hole on the corresponding atom, which allows accurate simulation of various edges. It is also possible to go beyond DFT using many-body perturbation theories such as the GW approximation or the Bethe–Salpeter approach (BSE). The fully relativistic BSE method treats electron–hole interactions in a much more rigorous way and allows a proper description of the L2,3 edges of early transition-metal compounds.
{"title":"WIEN2k, an augmented plane wave plus local orbital package for the electronic structure of solids","authors":"P. Blaha","doi":"10.1107/s1574870720003171","DOIUrl":"https://doi.org/10.1107/s1574870720003171","url":null,"abstract":"WIEN2k is a versatile and user-friendly code for calculating the electronic structure of solids. It is based on density-functional theory (DFT) and can use a wide variety of different functionals. It utilizes the augmented plane-wave method and treats all electrons (core and valence) self-consistently, making it a very accurate method. It calculates the basic electronic structure, allows structure optimization and can simulate various spectroscopies. For X-ray absorption or electron energy-loss spectroscopy, excitonic effects can be considered using a core hole on the corresponding atom, which allows accurate simulation of various edges. It is also possible to go beyond DFT using many-body perturbation theories such as the GW approximation or the Bethe–Salpeter approach (BSE). The fully relativistic BSE method treats electron–hole interactions in a much more rigorous way and allows a proper description of the L2,3 edges of early transition-metal compounds.","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132361213","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 : 2020-12-21DOI: 10.1107/s1574870720003432
C. Prestipino
{"title":"PrestoPronto: a software package for large EXAFS data sets","authors":"C. Prestipino","doi":"10.1107/s1574870720003432","DOIUrl":"https://doi.org/10.1107/s1574870720003432","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"201 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132752319","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 : 2020-12-21DOI: 10.1107/s1574870720003511
A. Kodre, I. Arčon, J. Padežnik Gomilšek
{"title":"Photoexcitation processes in atoms","authors":"A. Kodre, I. Arčon, J. Padežnik Gomilšek","doi":"10.1107/s1574870720003511","DOIUrl":"https://doi.org/10.1107/s1574870720003511","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132064896","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 : 2020-12-21DOI: 10.1107/s1574870720003481
M. Winterer
{"title":"xafsX: a program to process, analyse and reduce X-ray absorption fine structure spectra (XAFS)","authors":"M. Winterer","doi":"10.1107/s1574870720003481","DOIUrl":"https://doi.org/10.1107/s1574870720003481","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123647147","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 : 2020-12-21DOI: 10.1107/s1574870720003353
B. Ravel, M. Newville
{"title":"ATHENA and ARTEMIS","authors":"B. Ravel, M. Newville","doi":"10.1107/s1574870720003353","DOIUrl":"https://doi.org/10.1107/s1574870720003353","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133166533","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 : 2019-07-15DOI: 10.1107/97809553602060000985
J. Kaduk
{"title":"Powder diffraction in the petroleum and petrochemical industries","authors":"J. Kaduk","doi":"10.1107/97809553602060000985","DOIUrl":"https://doi.org/10.1107/97809553602060000985","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121581821","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 : 2019-07-15DOI: 10.1107/97809553602060000963
O. Magdysyuk, S. V. Smaalen, R. Dinnebier
This chapter provides a comprehensive overview of the maximum-entropy method (MEM) as it is applied to X-ray powder-diffraction data for computation of an unbiased electron-density map. The MEM requires a strictly positive electron-density map that is described by its values on a fine grid over the unit cell (with grid sizes of approximately 0.04 A). The entropy is defined for such a gridded density and the role of the prior or reference density is discussed. An in-depth presentation is given of the crystallographic MEM equations and the various iterative algorithms for solving these equations. All these considerations apply equally well to single-crystal and X-ray powder-diffraction data. The experimental data are incorporated into the MEM through constraints involving the structure factors. Specific to powder diffraction are the various methods for extracting estimates of the structure-factor amplitudes or group amplitudes, the use of G constraints in addition to F constraints on single-crystal diffraction data and the various methods of estimating the phases of the structure factors. This then leads to the definition of various types of MEM maps that range from maps completely biased by a structure model to ab initio electron-density maps. Irrespective of the type of MEM, series-termination effects are much less prominent in MEM-optimized electron-density maps than in Fourier maps obtained with the same data. Applications of the MEM are discussed concerning its use for improving structure models (e.g. the MEM + Rietveld method), its use for the characterization of disorder and anharmonic motion within crystal structures, its use as part of a protocol for structure solution, its use as an alternative to multipole refinements, and its application to electron densities in superspace for aperiodic crystals.
{"title":"Application of the maximum-entropy method to powder-diffraction data","authors":"O. Magdysyuk, S. V. Smaalen, R. Dinnebier","doi":"10.1107/97809553602060000963","DOIUrl":"https://doi.org/10.1107/97809553602060000963","url":null,"abstract":"This chapter provides a comprehensive overview of the maximum-entropy method (MEM) as it is applied to X-ray powder-diffraction data for computation of an unbiased electron-density map. The MEM requires a strictly positive electron-density map that is described by its values on a fine grid over the unit cell (with grid sizes of approximately 0.04 A). The entropy is defined for such a gridded density and the role of the prior or reference density is discussed. An in-depth presentation is given of the crystallographic MEM equations and the various iterative algorithms for solving these equations. All these considerations apply equally well to single-crystal and X-ray powder-diffraction data. The experimental data are incorporated into the MEM through constraints involving the structure factors. Specific to powder diffraction are the various methods for extracting estimates of the structure-factor amplitudes or group amplitudes, the use of G constraints in addition to F constraints on single-crystal diffraction data and the various methods of estimating the phases of the structure factors. This then leads to the definition of various types of MEM maps that range from maps completely biased by a structure model to ab initio electron-density maps. Irrespective of the type of MEM, series-termination effects are much less prominent in MEM-optimized electron-density maps than in Fourier maps obtained with the same data. Applications of the MEM are discussed concerning its use for improving structure models (e.g. the MEM + Rietveld method), its use for the characterization of disorder and anharmonic motion within crystal structures, its use as part of a protocol for structure solution, its use as an alternative to multipole refinements, and its application to electron densities in superspace for aperiodic crystals.","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121698865","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 : 2019-07-15DOI: 10.1107/97809553602060000981
N. Scarlett, D. Bish
{"title":"Mining and mineral processing","authors":"N. Scarlett, D. Bish","doi":"10.1107/97809553602060000981","DOIUrl":"https://doi.org/10.1107/97809553602060000981","url":null,"abstract":"","PeriodicalId":338076,"journal":{"name":"International Tables for Crystallography","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126156183","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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