DEBUSSY: a Debye user system for nanocrystalline materials

DEBUSSYis a new free open-source package, written in Fortran95 and devoted to the application of the Debye function analysis (DFA) of powder diffraction data from nanocrystalline, defective and/or non-periodic materials through the use of sampled interatomic distance databases. The suite includes a main program, taking the name of the package,DEBUSSY, and dealing with the DFA of X-ray, neutron and electron experimental data, and a suite of 11 programs, namedCLAUDE, enabling users to create their own databases for nanosized crystalline materials, starting from the list of space-group generators and the asymmetric unit content. A new implementation of the Debye formula is adopted inDEBUSSY, which makes the approach fast enough to deal with the pattern calculation of hundreds of nanocrystals, to sum up their contributions to the total pattern and to perform iterative algorithms for optimizing the parameters of the pattern model. The package strategy uses the sampled-distance database(s) created previously byCLAUDEand combines, for any phase, a log-normal or a bivariate log-normal function to deal with the sample-size distribution; four different functions are implemented to manage possible lattice expansions/contractions as a function of crystal size. A number of output ASCII files are produced to supply some statistics and data suitable for graphical use. The databases of sampled interatomic non-dimensional distances for cuboctahedral, decahedral and icosahedral structure types, suitable for dealing with noble metal nanoparticles, are also available.