DIFFUSE: a procedure to measure diffuse intensity on a CAD-4 diffractometer with CAD-4-EXPRESS software

An inaccuracy in the GRIDSCAN procedure, included in version 5.1 of CAD-4-EXPRESS, is pointed out. The program presented allows interactive and batch-type scans on a true grid in reciprocal-lattice units. Two measurement modes are provided: (i) calculation of all points at general Eulerian angles with fixed ψ for all reflections; (ii) two-circle geometry by definition of a zone axis.