PEPC is a parallel tree-code for rapid computation of long-range (1/r) Coulomb forces for large ensembles of charged particles. The heart of the code is a Barnes-Hut style algorithm employing multipole expansions to accelerate the potential and force sums, leading to a computational effort O(NlogN) instead of the O(N2) which would be incurred by direct summation. Parallelism is achieved via a `Hashed Oct Tree' scheme, which uses a space-filling curve to map the particle coordinates onto processors. The kernel (tree routines and force computation) is separated from the application `front-end' so that the code can be easily adapted to both electrostatic and gravitational problems.
Currently this code family consists of:
- PEPC-B for modeling high-intensity laser and particle beam interactions with dense plasmas
- PEPC-E, a stand-alone Coulomb-solver code with a transparent interface to the kernel.
- PEPC-G = PEGS for studying star-disc encounters.
The DEISA benchmark version uses the PEPC-E front-end. It is the first code to employ a mesh-free algorithm for modeling kinetic (non-fluid) phenomena such as non-local electron transport and particle acceleration in dense plasmas. In contrast to traditional mesh-based Particle-in-Cell codes, PEPC-E can operate in a fully collisional or strongly coupled regime, and can tackle open-boundary problems. Currently PEPC is being used to investigate ion acceleration in Petawatt laser-plasma interactions - issues relevant to the Fast Ignitor Laser-Fusion concept (HIPER, ELI).