This work was supported by the NIST Materials Science and Engineering Laboratory, Ceramics Division, and the Center for Theoretical and Computational Materials Science. We appreciate useful discussions with A. Roosen, J. Blendell, J. Warren, R. Braun, J. Taylor, C. Handwerker and Hub Aaronson. We are also grateful to contribute to this acknowledgement of Hub Aaronson's lasting contributions to our field.