where N I is the number of solvent molecules, b ρ is a force constant (determining the build-up rate), a k and w ρ,k are the position and weight associated with grid point k, ω ρ is the kernel width in grid units and ∆ is the grid spacing. The latter is given by ∆ = K -1 a max , where a max is 1/2 in slab geometry and 3 1/2 /2 in spherical geometry. There are three main differences in the procedure compared to the standard LEUS scheme . First, the factor ω ρ is introduced which, when differing from 1, permits to make the correction potential smoother. Second, all solvent molecules are coupled to the same (one-dimensional) correction potential. Third, a molecule I at grid point