Modeling and optimization algorithm to analyse xrpd data via modulation and pseudo-voigt functions

摘要

The composition of the sample related-effects with those from the instrument, has been carried out by convolution of involved terms. The sample-related effects have been modelled via the modulation function accounting for packed parallel planes, named here "layers", and other structure-related parameters. The instrumental parameters have been determined using DISVAR93, a software package allowing the diffraction profiles to be represented in the more convenient shape of a pseudo-Voight function. A constrained optimization process is the basis for determining these instrumental parameters, their calibration is typically carried out by adopting an external standard sample. The comparison of the modeled intensity distribution with the experimental one is performed via minimization of _X2; where the convolutor and minimizator are embedded engines of the algorithm.