INTERACTIONS AT THE ORGANIC INORGANIC INTERFACE - MOLECULAR MODELING OF THE INTERACTION BETWEEN DIPHOSPHONATES AND THE SURFACES OF BARITE CRYSTALS/

Molecular modeling techniques are used to investigate the interaction of alkyldiphosphonate molecular anions with the surfaces of barium sul fate. We show that the most stable sites are on the (100) and (011) su rfaces with the [PO3](2-) groups of the diphosphonates replacing surfa ce sulfate ions. These results are compared with experimental observat ions; and analysis of the calculated energies demonstrates that the ov erall binding energy represents a subtle balance between the internal energy of the diphosphonate and the binding energy of the distorted di phosphonate in the site.