1. Contribution from the DEOS, Cranfield University, Defense Academy of the U.K., Shrivenham, Swindon, U.K., The Royal Institution of Great Britain, 21 Albemarle Street, London, U.K., Department of Chemistry, University College London, U.K., Materials Modeling Center, School of Physical and Mineral Sciences, University of Limpopo, P/Bag X 1106, Sovenga 0727, South Africa, and Manufacturing and Materials Technology, Council for the Scientific and Industrial Research, P.O. Box 392, Pretoria 0002, South Africa