Atom-based polychromatic diffraction pattern predictions for ultra-fast time-resolved experiemnts with large scale GPU-accelerated parallel simulation code*

To design and interpret single-shot ultra-fast time-resolved synchrotron- and XFEL-based diffraction experiments, it's desired to simulate the diffraction patterns directly from atomic configurations. GPU accelerated parallel simulation for direct, kinematics-based, simulations of x-ray/electron diffraction of large-scale atomic systems with mono-/polychromatic beams and arbitrary plane detector geometry is implemented here. With this code, nanocrystalline system size can be up to several billion atoms. In the system, nanocrystals can be of arbitrary crystal structures, grain shapes and sizes. Both X-ray and electron 2D diffraction patterns can be simulated with arbitrary beam energy in mono- or poly-chromatic beam cases. Intensities in reciprocal space can be directly exploded to help design experiment setups. The application to predict polychromatic diffraction pattern accounting for the polychromatic nature of x-ray implemented in ultra-fast time-resolved synchrotron- and XFEL-based experiments will presented.