Schematic presentation of the PIC code’s class relationship and connectivity. The FIELDS module is built on top of the CORGI module that provides the spatial simulation grid. It contains the electromagnetic fields Ê and , and the methods to advance them in time. The PIC module handles the computational particles. It is coupled to the FIELDS module via the current ĵ induced by the moving charged particles. Similarly, the FIELDS module is coupled to the PIC module by the Lorentz force.