Large-Scale Simulations of Laser-Cluster Interactions

Vikrant Saxena, Zoltan Jurek, Sang-Kil Son, Beata Ziaja, and Robin Santra

[BibTeX]http://www.dpg-verhandlungen.de/year/2014/conference/berlin/part/p/session/9/contribution/2

Imaging of complex molecules and clusters, using soft and hard X-ray free electron laser (FEL) radiation is an area of frontline research. Computer simulations of irradiated objects have proven to be very helpful in understanding imaging experiments. In the present numerical approach, the nanoparticle dynamics is modeled using molecular dynamics code, XMDYN [Z. Jurek et al.] with inputs from the atomic physics code, XATOM [S.-K. Son et al.]. This approach has been very successful in simulating the interaction of femtosecond X-ray pulses with small clusters and molecules, containing 105 atoms. Simulating large particles of 106 atoms, with a high degree of ionization, still remains a challenge, due to the O(N2) scaling of the computation time, N being the total number of atoms within the particle. In order to achieve a better scaling of computational efficiency with the particle size, we have recently implemented an improved BH-tree algorithm, into the XMDYN code, which brings the scaling down to O(NlogN ). The capability of the upgraded code, along with XATOM toolkit, to simulate the real time dynamics of large clusters triggered by ultrashort XFEL pulses, is demonstrated.

Tags: XATOM, XMDYN, CFEL, DESY