SC15 Austin, TX

Accelerating the B-Spline Evaluation in Quantum Monte Carlo

Authors: Ye Luo (Argonne National Laboratory), Anouar Benali (Argonne National Laboratory), Vitali Morozov (Argonne National Laboratory)

Abstract: In Quantum Monte Carlo simulations, the many-body Schrodinger equation can be solved with its wavefunction represented by B-splines which is computationally less intensive O(N^2) than the commonly used planewaves O(N^3). Despite the high efficiency of B-splines, the wavefunction evaluation still takes over 20% of the total application time. We recently improved the algorithm by fully taking advantage of the vectorization and optimizing the memory access on BG/Q and achieved about 3-fold speedup in the subroutines calculating multiple B-splines. Threading capability is also added to the new algorithm to maximize the single node performance. According to the specifications of the upcoming HPC systems (long vector units, more integrated cores, higher memory bandwidth), all the methods used to design the new algorithm make it ready to efficiently exploit the new features of these systems.

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