A binding site location for docking is specified using one or more centroids, each consisting of the Cartesian coordinate of its center and its radius. We generate a binding site grid that covers the space of all centroids that represent the binding site (Figure ). We use an HCP grid that provides maximal packing efficiency, covering the same volumetric space of a simple cubic grid with approximately 40 % fewer grid points to achieve the same maximal interstitial spacing.