Since the complex has the same three bipyridine ligands, one can place in total three and : A [Fe(bpy) 3 ] 2+ complex and noncovalently-bonded water molecule(s), the potential energy curve of which is studied in LS and HS states. Only complex-water interaction is present in subfigures a and b, whereas both complex-water and water-water interactions exist in subfigures c-f. Note that, for the later, the oxygen atom of the water molecule, the distance of which is varied, is colored in yellow.