X-ray free-electron laser (XFEL) pulses represent an unprecedented tool to follow dynamics on femtosecond timescales and determine structure with Angstrom resolution. Since these pulses contain high photon number, multiphoton interaction is almost unavoidable in the focused beam. Thus, it is of fundamental interest to understand the correlated electron and nuclear dynamics within the sample for any application, most notably for single particle imaging where ultraintense focused x-ray pulses are required. Developments are also underway to improve temporal coherence and add novel features to the pulse operation mode, such as two-color femtosecond pulses. These new capabilities further motivate detailed understanding of the fundamental interactions of XFEL pulses with atoms and molecules as they can impact potential applications such as following chemical dynamics in real time, performing structural analysis, initiating and controlling inner-shell processes, and exploring nonlinear phenomena in atoms and molecules and complex materials. In this talk, I will give an overview of our theoretical efforts and challenges in following the ultrafast transient dynamics in various systems (from atoms to nano-sized clusters) exposed to intense XFEL pulses. Also, I will also describe our recent computational codes that can hardness the enormous computational power of the current high-performance computing resources, such as the Mira and Theta supercomputer at Argonne Leadership Computing Facility.

Theoretical investigations of the ultrafast correlated electronic and nuclear dynamics in intense x-ray pulses: From atoms to clusters

256th National Meeting (2018)

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