10.2: Isomorphous replacement Last updated Save as PDF Page ID 17337 Online Dictionary of Crystallography International Union of Crystallography Figure: Principle of the isomorphous replacement method for structure solution. F 1 and F 2 represent the total structure factor from two isomorphous crystals for a given reflection, ΔF is their difference. The angles φ 1 and φ ΔF are the phases of F 1 and ΔF, they are related via φ.