Accelerating Quantum Light-Matter Dynamics on Graphics Processing Units

We have developed a simulation method to study how electrons interact with an external laser pulse by solving the Maxwell equation for electrons and time-dependent density functional theory equations for electrons. We present an efficient way to perform electronic time-propagation as well as to reformulate the compute-intensive nonlocal correction into matrix operations, which resulted in a 644-fold speedup on Nvidia A100 GPU over AMD EPYC 7543 CPU of the Polaris computer at Argonne Leadership Computing Facility. In addition, the resulting DC-MESH (divide-&conquer Maxwell-Ehrenfest-surface hopping) code exhibited a weak-scaling parallel efficiency of 96.73% on 256 nodes (or 1,024 GPUs) of Polaris for 5,120-atom PbTiO₃ material. This enables the study of light-induced topological switching for future ultrafast and ultralow-power ferroelectric topotronics applications.