Starting from a lattice dynamical model derived from periodic ab-initio calculations we are developing a method to refine a common vibrational model against diffraction data collected at several temperatures. It is possible within this model to incorporate the effect of thermal diffuse scattering. In order to test and develop the model, we need high-quality neutron diffraction data on a model system. The data should be collected at several temperatures, using an area detector, in order to measure the thermal diffuse scattering. We propose to collect multi-temperature neutron diffraction data on melamine, a model system where X-ray data are already available at 10, 122, 172 and 222 K. A detailed comparison with neutron diffraction data, including corrections for thermal diffuse scattering, will help us determine the reasons for the well-known differences between ADPs obtained from X-ray and neutron diffraction experiments.