Plot of atomic form factor v scattering vector Q

These animations plot the atomic form factor f^{0} as a function of Q, the scattering vector (below left), and as a function of polar angle and photon energy (below right). Also plotted in the lefthand plot is the maximum accessible Q-value for a given photon energy, given by , and the corresponding minimum resolution a_{min} that can be obtained in diffraction experiments. For both matlab codes, the user can enter an input data file containing the nine parameters used to generate the atomic form factor from four Gaussians and a constant for any given element. This data can be found e.g., here. The data file is a simple single-column text file containing 9 rows. An example for selenium can be found here. If no data file is provided, the program takes the values for sulphur as default. The range and step size of photon energies are also optional input parameters.