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A program to analyze the distributions of unmeasured reflections
Author(s) -
Urzhumtseva Ludmila,
Urzhumtsev Alexandre
Publication year - 2011
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/s0021889811019546
Subject(s) - completeness (order theory) , missing data , set (abstract data type) , reciprocal , computer science , algorithm , data set , fourier transform , diffraction , data quality , data mining , distribution (mathematics) , mathematics , mathematical analysis , artificial intelligence , optics , physics , machine learning , metric (unit) , linguistics , philosophy , operations management , economics , programming language
Crystallographic Fourier maps may contain barely interpretable or non‐interpretable regions if these maps are calculated with an incomplete set of diffraction data. Even a small percentage of missing data may be crucial if these data are distributed non‐uniformly and form connected regions of reciprocal space. Significant time and effort can be lost trying to interpret poor maps, in improving them by phase refinement or in fighting against artefacts, whilst the problem could in fact be solved by completing the data set. To characterize the distribution of missing reflections, several types of diagrams have been suggested in addition to the usual plots of completeness in resolution shells and cumulative data completeness. A computer program, FOBSCOM , has been developed to analyze the spatial distribution of unmeasured diffraction data, to search for connected regions of unmeasured reflections and to obtain numeric characteristics of these regions. By performing this analysis, the program could help to save time during structure solution for a number of projects. It can also provide information about a possible overestimation of the map quality and model‐biased features when calculated values are used to replace unmeasured data.