The estimation of three-phase invariants when anomalous scatterers are present: the limits.
The probabilistic formula provided by Hauptman and Giacovazzo for estimating three-phase invariants when anomalous scatterers are present is revisited. Its main defects are: (a) it is absolutely resistant to any attempt at interpreting it in terms of parameters accessible via the experiment; (b) its calculation is time consuming and requires computing resources. A distribution based on interpretable estimates of the parameters is proposed. The role of the old and the new expressions in the single-wavelength anomalous diffraction (SAD) techniques is discussed, and compared with the role of analogous formulas estimating triplet invariants from isomorphous diffraction data.
Dipartimento Geomineralogico, Università di Bari, Campus Universitario, Via Orabona 4, 70125 Bari, Italy. carmelo.giacovazzo@ic.cnr.it
Carmelo
C
Giacovazzo
Massimo
M
Ladisa
Dritan
D
Siliqi