Refining a model electron-density mapviathePhantom Derivativemethod

Abstract

ThePhantom Derivative(PhD) method [Giacovazzo (2015),Acta Cryst.A71, 483–512] has recently been described forab initioand non-ab initiophasing. It is based on the random generation of structures with the same unit cell and the same space group as the target structure (called ancil structures), which are used to create derivatives devoid of experimental diffraction amplitudes. In this paper, the non-ab initiovariant of the method was checked using phase sets obtained by molecular-replacement techniques as a starting point for phase extension and refinement. It has been shown that application ofPhDis able to extend and refine phases in a way that is competitive with other electron-density modification techniques.