Efficient Implementations of Molecular Dynamics Simulations for Lennard-Jones Systems

TL;DR

This paper presents efficient algorithms and architecture-specific techniques for molecular dynamics simulations of Lennard-Jones particles, demonstrating high parallel efficiency on large-scale CPU clusters through benchmark tests.

Contribution

It introduces optimized implementations and parallelization strategies for MD simulations on specific CPU architectures, with detailed performance analysis.

Findings

Parallelization efficiency reaches about 73% with 8192 MPI processes.

Fluctuations in process execution times impact parallel efficiency.

OS Jitter contributes to performance degradation.

Abstract

Efficient implementations of the classical molecular dynamics (MD) method for Lennard-Jones particle systems are considered. Not only general algorithms but also techniques that are efficient for some specific CPU architectures are also explained. A simple spatial-decomposition-based strategy is adopted for parallelization. By utilizing the developed code, benchmark simulations are performed on a HITACHI SR16000/J2 system consisting of IBM POWER6 processors which are 4.7 GHz at the National Institute for Fusion Science (NIFS) and an SGI Altix ICE 8400EX system consisting of Intel Xeon processors which are 2.93 GHz at the Institute for Solid State Physics (ISSP), the University of Tokyo. The parallelization efficiency of the largest run, consisting of 4.1 billion particles with 8192 MPI processes, is about 73% relative to that of the smallest run with 128 MPI processes at NIFS, and it is about 66% relative to that of the smallest run with 4 MPI processes at ISSP. The factors causing the parallel overhead are investigated. It is found that fluctuations of the execution time of each process degrade the parallel efficiency. These fluctuations may be due to the interference of the operating system, which is known as OS Jitter.