Reconsidering Dispersion Potentials: Reduced Cutoffs in Mesh-Based Ewald Solvers Can Be Faster Than Truncation

Long-range dispersion interactions have a critical influence on physical quantities in simulations of inhomogeneous systems. However, the perceived computational overhead of long-range solvers has until recently discouraged their implementation in molecular dynamics packages. Here, we demonstrate that reducing the cutoff radius for local interactions in the recently introduced particle–particle particle−mesh (PPPM) method for dispersion [Isele-Holder et al., J. Chem. Phys., 2012, 137, 174107] can actually often be faster than truncating dispersion interactions. In addition, because all long-range dispersion interactions are incorporated, physical inaccuracies that arise from truncating the potential can be avoided. Simulations using PPPM or other mesh Ewald solvers for dispersion can provide results more accurately and more efficiently than simulations that truncate dispersion interactions. The use of mesh-based approaches for dispersion is now a viable alternative for all simulations containing dispersion interactions and not merely those where inhomogeneities were motivating factors for their use. We provide a set of parameters for the dispersion PPPM method using either ik or analytic differentiation that we recommend for future use and demonstrate increased simulation efficiency by using the long-range dispersion solver in a series of performance tests on massively parallel computers.长程色散相互作用对非均匀体系模拟中的物理量具有关键影响。然而，长期以来人们对长程求解器的计算开销的固有认知，曾阻碍了其在分子动力学软件包中的部署应用。本文证实，针对近期提出的色散用粒子-粒子粒子网格（particle–particle particle−mesh，PPPM）方法中的局域相互作用截断半径进行优化，其实际运算效率往往优于直接截断色散相互作用的方案[Isele-Holder et al., J. Chem. Phys., 2012, 137, 174107]。此外，由于该方法纳入了全部长程色散相互作用，可避免因截断势能而引入的物理计算误差。采用PPPM或其他网格埃瓦尔德求解器进行色散相互作用模拟，相较于直接截断色散相互作用的模拟方案，能够以更高的效率获得更为准确的计算结果。如今，基于网格的色散相互作用处理方法，已成为所有包含色散相互作用的模拟场景的可行替代方案，而非仅适用于以非均匀体系为研究动机的模拟工作。我们针对色散PPPM方法，提供了采用ik或解析微分的两套参数方案，以供后续研究使用；并通过在大规模并行计算机上开展的一系列性能测试，验证了长程色散求解器可有效提升模拟效率。