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Peak labelling in electron density maps from powder data: the use of crystal chemical information
Author(s) -
Altomare Angela,
Giacovazzo Carmelo,
Ianigro Massimo,
Moliterni Anna Grazia Giuseppina,
Rizzi Rosanna
Publication year - 2002
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889801016739
Subject(s) - labelling , truncation (statistics) , crystal (programming language) , electron density , representation (politics) , powder diffraction , electron , diffraction , series (stratigraphy) , crystallography , materials science , chemistry , computational physics , molecular physics , physics , mathematics , computer science , optics , statistics , quantum mechanics , paleontology , biochemistry , politics , political science , law , biology , programming language
Direct methods applied to powder diffraction data often provide electron density maps of which the quality is usually affected by systematic and/or random phase errors, by amplitude truncation effects in the series representation of the electron density, etc . The frequent incorrect labelling of the peaks can strongly affect the efficiency of the procedures used for crystal structure refinement. For example, the success of alternative techniques, such as POLPO [Altomare et al . (2000). J. Appl. Cryst. 33 , 1305–1310], requires that all the heavy atoms be positioned and exactly labelled.