sentences: Technological advances have made FPGAs an attractive platform for the acceleration of complex scientific applications. These applications demand high performance and hi ghprecision floating point arithmetic. In this paper, we present a design for calculating the Lennard-Jones potential and for ce as is done in molecular dynamics simulations. This architecture employs IEEE 754 double precision floating point units, incl uding a square root unit developed for this kernel. The design pres ented is a modular, very deeply pipelined architecture that exploits the fine-grained parallelism of the calculations. With the Xilinx Virtex-II Pro as a target device, an implementation using two pipelines operating in parallel achieves 3.9 GFLOPS.