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A new density-modification procedure extending the application of the recent |ρ|-based phasing algorithm to larger crystal structures
13 July 2021
The incorporation of the new peakness-enhancing fast Fourier transform compatible ipp procedure (ipp = inner-pixel preservation) into the recently published SM algorithm based on |ρ| [Rius (2020). Acta Cryst A76, 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 http://reference.iucr.org/dictionary/Unit_cell", 'Navigator')" style="text-decoration: none; color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;">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 SM algorithm is simple, since it only includes a few easy-to-adjust parameters.
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Oxides for new-generation electronics

A new density-modification procedure extending the application of the recent |ρ|-based phasing algorithm to larger crystal structures


Jordi Rius* and Xavier Torrelles

Acta Cryst. (2021). A77339-347

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