Figure 14.

FMM versus PME performance in GROMACS for salt water (top) and multidroplet (bottom) benchmarks. Settings were chosen such that PME and FMM yield similar accuracies of electrostatic forces as well as comparable energy drifts. FMM used p = 8 and d = 3, whereas PME used the “default” parameter set (r_c = 1.0 nm, PME grid spacing s = 0.12 nm, fourth order interpolation, see Figure 9). For the multidroplet system, for optimal PME performance, both r_c and s were scaled by a factor of 2.943, which leaves the PME accuracy essentially unchanged.