Toward an FPGA-based dedicated computer for molecular dynamics simulations.

First steps toward a molecular dynamics (MD) implementation in a cluster of field-programmable gate arrays (FPGAs) are presented, reaching a simulation speed of a few microseconds/day. The nodes in this cluster are programmed into a mid-ranged FPGA (Artix 7 XC7A200T), interconnected as a 3D torus by fast optical links. The implemented MD algorithm is highly parallelized and highly pipelined internally. The FPGA cluster is freely scalable in terms of size, i.e., a larger MD system requires more nodes, however, without compromising simulation speed. The performance in terms of energy stability and simulation speed is analyzed. At present, the focus lies on the fast networking, while only minimal MD functionality has been implemented so far, i.e., Lennard-Jones interactions and a thermostat, which were needed to demonstrate the feasibility of the FPGA cluster to run multi-microsecond simulations. To that end, the nucleation of a super-cooled Lennard-Jones liquid is investigated by unbiased MD simulations, which is a difficult MD problem since a high nucleation barrier has to be overcome. Finally, the pathways toward a full MD implementation are outlined. The current implementation will be made available as an open-source development project.