Evaluating scattering data of the micro and nano scale by computer simulations with a focus on hydrogen storage materials

by Arnab Majumdar (Helmholtz Zentrum hereon)

Monday 3 Jul 2023, 14:30 → 15:30 Europe/Berlin

PH HS 3 (Physics Department)

Scattering experiments are useful techniques for the investigation of materials at length scales from Angstroms to nanometers but they suffer from underdetermination due to the phase problem. Molecular Dynamics (MD) and continuum simulations can build models that help to understand the scattering patterns. However, the computation of scattering patterns from these simulations is not a trivial process. In principle, the calculation of scattering patterns from MD simulations is well established but suffers from long computation times.

Additionally, one sees the shape and size of the finite simulation box in the small angle scattering region, overlaying the information about the actual sample within the box. The calculation of scattering patterns from continuum simulations is so far much less explored. This work addresses these problems. An improvement in computation time of up to about an order of magnitude was achieved for diffraction. A method for removing the spurious signal caused by the finite simulation box size at small scattering angles is demonstrated on the example of a protein in water and validated against experimental data. The method for the treatment of continuum simulations is validated for simple shapes where analytical expressions can be used as reference. 

Furthermore, this work uses the above mentioned methods for the investigation of a hydrogen storage material. Nanoscopic information is extracted from small angle neutron scattering of hydrogen storage materials and this information is used to understand the system at the engineering scale of millimeters.