Structure and energetics of LiF chains as a model for low dimensional alkali halide nanocrystals

Nanocrystals of inorganic salts constrained in geometry by encapsulation in single walled carbon nanotubes have been shown by recent high-resolution transmission electron microscopy experiments to exhibit specific distortions of their structure in comparison with the ideal bulk. These structural distortions of low dimensional crystallites are analyzed within the Hartree-Fock approximation and density functional theory based on the simplest alkali halide chains, LiF. The observed patterns of distortions in the structure of nanocrystals are the results of low dimensionality and the axial strain (end effects). The structural trends calculated ab initio for LiF are compared with analytical predictions based on the traditional Born theory of bulk crystals and experiments. The energetics of the LiF crystallites is discussed. (c) 2006 Elsevier B.V. All rights reserved.