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A new density‐modification procedure extending the application of the recent |ρ|‐based phasing algorithm to larger crystal structures
Author(s) -
Rius Jordi,
Torrelles Xavier
Publication year - 2021
Publication title -
acta crystallographica section a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.742
H-Index - 83
ISSN - 2053-2733
DOI - 10.1107/s2053273321004915
Subject(s) - phaser , algorithm , crystal structure , fourier transform , crystal (programming language) , phase (matter) , materials science , resolution (logic) , simple (philosophy) , function (biology) , crystallography , computational physics , computer science , physics , chemistry , optics , mathematics , mathematical analysis , programming language , philosophy , epistemology , quantum mechanics , artificial intelligence , evolutionary biology , biology
The incorporation of the new peakness‐enhancing fast Fourier transform compatible ipp procedure ( ipp = inner‐pixel preservation) into the recently published S M algorithm based on |ρ| [ Rius (2020). Acta Cryst A 76 , 489–493] improves its phasing efficiency for larger crystal structures with atomic resolution data. Its effectiveness is clearly demonstrated via a collection of test crystal structures (taken from the Protein Data Bank) either starting from random phase values or by using the randomly shifted modulus function (a Patterson‐type synthesis) as initial ρ estimate. It has been found that in the presence of medium scatterers ( e.g. S or Cl atoms) crystal structures with 1500 × c atoms in the unit cell ( c = number of centerings) can be routinely solved. In the presence of strong scatterers like Fe, Cu or Zn atoms this number increases to around 5000 × c atoms. The implementation of this strengthened S M algorithm is simple, since it only includes a few easy‐to‐adjust parameters.