Many of the steps reported in 3.1 require the computation of electrostatic interactions and are natively quadratically scaling. Such steps are computing the RHS F, solving the linear systems for ddPCM and ddLPB, computing the solvation contribution to the forces for ddPCM and ddLPB, and finally computing the solute contribution to the forces. All of these steps are accelerated with the FMM and are linear scaling in N , except for the initialization, which scales like N log(N ).