A New Method to Model the Dynamic Structure Factor by Molecular Dynamics Simulations

Research Project, 2017 – 2020

In this collaborative project between Chalmers, ESS, ISIS and the Niels Bohr Institute we aim to overcome the difficulty to interpret and understand inelastic and quasielastic neutron scattering data by developing a new computer modelling method to model the dynamic structure factor, S(Q,w). S(Q,w) will be calculated in a molecular dynamics (MD) simulation and the interatomic potentials will be changed until a quantitative agreement is obtained between the calculated S(Q,w) of the MD model and the measured S(Q,w). Hence, the method is a dynamical correspondence to the Empirical Potential Structure Refinement (EPSR) method used to produce structural models of materials in quantitative agreement with neutron and x-ray diffraction data. It is foreseen that our approach will have the same huge impact on understanding the dynamics as EPSR has on structure. Thus, ESS, ISIS and their user community will benefit enormously by the development of the proposed method. It will be possible to obtain a considerably deeper understanding of how the macroscopic properties of materials depend on the molecular motions in them. Thereby, it will also be possible to gain insights into how new materials in the areas of chemistry, biology, life science and medicine can be improved. Moreover, not only the users of neutron spectroscopy will take advantage of the method, but also the computer simulation community will get a unique possibility to refine model potentials by using this approach.