Spurzem, Rainer 

How to build and use special purpose PC clusters in stellar dynamics 

Full Text pdf; Direct Link CUP; Proceedings of the International Astronomical Union, Highlights of Astronomy 14, 426-427, Cambridge University Press (2007)

Abstract: Large scale, direct particle-particle, brute force N-body simulations are required to accurately resolve numerically transport processes of energy and angular momentum due to two-body relaxation, and interactions between supermassive black holes and other particles having a much smaller mass. Direct accurate N-body codes are the widely used tool for such simulations, e.g., NBODY4 or NBODY6 (Aarseth 1999, 2003), see also Harfst et al. (2007) for a less complex code variant, used for benchmarks in this paper. Makino (2002) has presented another direct N-body summation code, which is optimized for a quadratic layout of processor (p required to be a square number).