Refining a model electron-density map via the Phantom Derivative method.
The Phantom Derivative (PhD) method [Giacovazzo (2015), Acta Cryst. A71, 483-512] has recently been described for ab initio and non-ab initio phasing. 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 initio variant 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 of PhD is able to extend and refine phases in a way that is competitive with other electron-density modification techniques.
Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy.
Maria Cristina
MC
Burla
Istituto di Cristallografia, CNR, Via G. Amendola 122/o, 70126 Bari, Italy.
Benedetta
B
Carrozzini
Istituto di Cristallografia, CNR, Via G. Amendola 122/o, 70126 Bari, Italy.
Giovanni Luca
GL
Cascarano
Istituto di Cristallografia, CNR, Via G. Amendola 122/o, 70126 Bari, Italy.
Carmelo
C
Giacovazzo
Istituto di Cristallografia, CNR, Via G. Amendola 122/o, 70126 Bari, Italy.
Giampiero
G
Polidori
D004583:Electrons; D008958:Models, Molecular; D015394:Molecular Structure
Phantom Derivative method; molecular replacement; phase refinement; phasing