About difference electron densities and their properties
| Autor: | Maria Cristina Burla, Giampiero Polidori, Carmelo Giacovazzo, Giovanni Luca Cascarano, Benedetta Carrozzini |
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| Rok vydání: | 2017 |
| Předmět: |
amplitudes
Ab initio 02 engineering and technology Electron Crystal structure 010403 inorganic & nuclear chemistry 01 natural sciences Biochemistry Molecular physics Inorganic Chemistry Structural Biology Computational chemistry Phase (matter) errors General Materials Science Joint distribution function Physical and Theoretical Chemistry Connection (algebraic framework) difference Fourier synthesis phasing EDM-DEDM phases Physics difference Fourier syntheses joint probability distribution functions 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences Amplitude 0210 nano-technology |
| Zdroj: | Acta crystallographica. Section A, Foundations of crystallography 73 (2017): 460–473. doi:10.1107/S2053273317011585 info:cnr-pdr/source/autori:Burla M.C. 1-2); Carrozzini B. 2); Cascarano G.L. 2); Giacovazzo C. 2); Polidori G. 2)/titolo:About difference electron densities and their properties/doi:10.1107%2FS2053273317011585/rivista:Acta crystallographica. Section A, Foundations of crystallography/anno:2017/pagina_da:460/pagina_a:473/intervallo_pagine:460–473/volume:73 |
| ISSN: | 2053-2733 |
| Popis: | Difference electron densities do not play a central role in modern phase refinement approaches, essentially because of the explosive success of the EDM (electron-density modification) techniques, mainly based on observed electron-density syntheses. Difference densities however have been recently rediscovered in connection with theVLD(Vive la Difference) approach, because they are a strong support for strengthening EDM approaches and forab initiocrystal structure solution. In this paper the properties of the most documented difference electron densities, here denoted asF−Fp,mF−FpandmF−DFpsyntheses, are studied. In addition, a fourth new difference synthesis, here denoted as {\overline F_q} synthesis, is proposed. It comes from the study of the same joint probability distribution function from which theVLDapproach arose. The properties of the {\overline F_q} syntheses are studied and compared with those of the other three syntheses. The results suggest that the {\overline F_q} difference may be a useful tool for making modern phase refinement procedures more efficient. |
| Databáze: | OpenAIRE |
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