We describe a new parallel, non-orthogonal-grid, three-dimensional electrom
agnetic particle-in-cell (EMPIC) code based on a finite-volume formulation.
This code uses a logically Cartesian grid of deformable hexahedral cells,
a discrete surface integral (DSI) algorithm to calculate the electromagneti
c field, and a hybrid logical-physical space algorithm to push particles. W
e investigate the numerical instability of the DSI algorithm for non-orthog
onal grids, analyse the accuracy for EMPIC simulations on non-orthogonal gr
ids, and present performance benchmarks of this code on a pal allel superco
mputer. While the hybrid particle push algorithm has a second-order accurac
y in space, the accuracy of the DSI field solve algorithm is between first
and second order for non-orthogonal grids. The parallel implementation of t
his code, which is almost identical to that of a Cartesian-grid EMPIC code
using domain decomposition, achieved a high parallel efficiency of over 96%
for large-scale simulations.