1. Contribution from the Laboratory of Macromolecular Physical Chemistry, UMR 7568 CNRS-INPL, ENSIC-INPL, BP 451, 54001 Nancy, France, and Laboratory of Crystallography and Modeling of Mineral and Biological Materials, ESA-7036, University Henri Poincaré of Nancy, BP 236, 54509 Vandoeuvre, France