Acta Crystallographica Section A · 1975 · 96 citations · 0 references
Natural SciencesChemistryPhysicsComputational ChemistryCrystal StructureTheoretical ChemistryCrystal ChemistryCrystal SymmetryCrystal SystemsCrystallographyStructure DeterminationX-ray CrystallographyCrystal InvariantsCrystal Structure AnalysisCrystal Structure DeterminationCrystal Symmetry AnalysisCrystal Symmetry DeterminationCrystallographic Point-group AnalysisPhase Determination
Recent theoretical advances in the identification of those cosine invariants cos (ϕh + ϕk + ϕ1 + ϕm) which are probably negative suggest algorithms for the calculation of a figure of merit which is sensitive to the integrity of a phase set. The negative quartet figure of merit, NQEST, defined here is of particular utility in conjunction with fast multi-solution tangent formula techniques. Development of the methods and applications to both known and unknown crystal structures are presented.