The method of joint probability distribution functions applied to MAD techniques. The two-wavelength case for acentric crystals

MAD (multiple-wavelength anomalous dispersion) techniques are often conside red as a special MIR (multiple isomorphous replacement) case. The rigorous method of the joint probability distribution functions is applied to solve the phase problem for acentric crystals, on the assumption that the anomalo us scatterer's substructure is a priori known. The two-wavelength case is c onsidered: errors in measurements and in the model substructure are handled . The probabilistic approach provides a very simple and efficient formula f or estimating structure-factor phases.