Parallel FFT-based Poisson Solver for Isolated Three-dimensional Systems
  We describe an implementation to solve Poisson's equation for an isolated system on a unigrid mesh using FFTs. The method solves the equation globally on mesh blocks distributed across multiple processes on a distributed-memory parallel computer. Test results to demonstrate the convergence and scaling properties of the implementation are presented. The solver is offered to interested users as the library PSPFFT. 
Reuben D. Budiardja and Christian Y. Cardall
physics.comp-ph