Coarse-grained potential for interaction with a spherical colloidal particle and planar wall

An effective coarse-grained interaction potential between a point particle and a sphericalcolloidal particle with continuously distributed inverse power-law interaction sites is de-rived. The potential covers all ranges of spherical particle size, from a point particle up to aninfinitely large particle forming a planar surface. In the small size limit, the point-to-pointinteraction is recovered, while in the limit of an infinitely large sphere the potential comesover to the known particle–wall potentials as, e.g., the 9–3 potential in the case of theLennard–Jones interaction. Correctness and usefulness of the derived potential is exempli-fied by its application to SPC/E water at a graphite sphere and wall.Keywords: Spherical colloidal particles; Surface interaction; Effective coarse-grained poten-tial; Molecular simulations; Water at graphite surface.