Image definition evaluation functions for X-ray crystallography: a new perspective on the phase problem

Acta Crystallographica. Section A, Foundations and Advances
Hui LiZe Zhang

Abstract

The core theme of X-ray crystallography is reconstructing the electron-density distribution of crystals under the constraints of observed diffraction data. Nevertheless, reconstruction of the electron-density distribution by straightforward Fourier synthesis is usually hindered due to the well known phase problem and the finite resolution of diffraction data. In analogy with optical imaging systems, the reconstructed electron-density map may be regarded as the image of the real electron-density distribution in crystals. Inspired by image definition evaluation functions applied in the auto-focusing process, two evaluation functions are proposed for the reconstructed electron-density images. One of them is based on the atomicity of the electron-density distribution and properties of Fourier synthesis. Tests were performed on synthetic data of known structures, and it was found that this evaluation function can distinguish the correctly reconstructed electron-density image from wrong ones when diffraction data of atomic resolution are available. An algorithm was established based on this evaluation function and applied in reconstructing the electron-density image from the synthetic data of known structures. The other evaluation fu...Continue Reading

References

Aug 14, 2003·Chemistry : a European Journal·Mátyás CzuglerPetra Bombicz
Feb 18, 2004·Acta Crystallographica. Section A, Foundations of Crystallography·Gábor Oszlányi, András Süto
Dec 25, 2007·Acta Crystallographica. Section A, Foundations of Crystallography·Gábor Oszlányi, András Süto
Feb 21, 2008·Acta Crystallographica. Section A, Foundations of Crystallography·Eaton Lattman, David DeRosier
Aug 1, 1982·Applied Optics·J R Fienup
May 2, 2015·Science·Jianwei MiaoMargaret M Murnane

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