Evaluation of Hybrid Parallel Cell List Algorithms for Monte Carlo Simulation

This paper describes efficient, scalable parallel implementations of the conventional cell list method and a modified cell list method to calculate the total system intermolecular Lennard-Jones force interactions in the Monte Carlo Gibbs ensemble. We targeted this part of the Gibbs ensemble for optimization because it is the most computationally demanding part of the force interactions in the simulation, as it involves all the molecules in the system. The modified cell list implementation reduces the number of particles that are outside the interaction range by making the cells smaller, thus reducing the number of unnecessary distance evaluations. Evaluation of the two cell list methods is done using a hybrid MPI+OpenMP approach and a hybrid MPI+CUDA approach. The cell list methods are evaluated on a small cluster of multicore CPUs, Intel Phi coprocessors, and GPUs. The performance results are evaluated using different combinations of MPI processes, threads, and problem sizes.