From Online Dictionary of Crystallography
Section de Harker (Fr). Harker-Ebene und Harker-Gerade (Ge).Sezione di Harker (It). ハーカー セクション (Ja). Sección de Harker (Sp).
In Patterson methods of structure solution, relationships between symmetrically related atoms produce peaks in the Patterson function on certain planes or along certain lines determined by the known crystallographic symmetries. Harker sections are portions of the Patterson map that contain a large proportion of the readily interpretable information because they contain many such Harker peaks (vectors between space-group equivalent atoms).