PERNOD - Ein Programm zur Verfeinerung von Kristallstrukturparametern aus Neutronenbeugungspulverdiagrammen

The program PERNOD described in this paper serves to refine crystal structure parameters from neutron powder diffraction data. The observed powder diagram is subdivided into groups of reflexions. The chosen boundaries of these groups are corrected by the program to obtain the best fit between a calculated line profile and the observed diagram. The observed intensities of reflexion groups obtained in this way are then split up into `observed' intensities of single reflexions using preliminary calculated reflexion intensities. The atomic parameters are refined using the ORFLS program, where the lattice constants are refined with the help of the line profile itself. As an example the atomic parameters of wolframite CuWO₄ are refined.