(775d) Reconsidering Dispersion Potentials: Using Reduced Cutoffs in Mesh-Based Ewald Solvers Can Eliminate the Performance Gap Versus Truncation

Long-range dispersion interactions play a major role in determining the physical quantities in simulations of inhomogeneous systems. However, because of the perceived computational cost of long-range solvers, their use in molecular dynamics packages has been discouraged. Here, we demonstrate that reducing the cutoff radius for local interactions in a recently implemented particle-particle particle-mesh (PPPM) method for dispersion [Isele-Holder et al., J. Chem. Phys., 137, 174107 (2012)] can, in many cases, actually be faster than simulations where dispersion interactions are simply truncated. In addition, because all long-range dispersion interactions are incorporated, this approach avoids the physical inaccuracies that arise from truncating the potential. Simulations using PPPM for dispersion can thus provide results that are both more accurate and more efficient than simulations that truncate dispersion interactions.

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 using several different architectures.