Useful applications of the electron localization function in high pressure crystal chemistry

The main features of a new computational code aimed at the topological analysis of the electron localization function (ELF) in crystals are hereby presented. Besides the complete localization of all critical points, the code is able to determine the limiting surfaces that define the chemical regions associated with the so-found maxima (or attractors) of the ELF. Hence, integrations of density operators within these basins provide charges and volumes to cores, bonds and lone pairs. Two illustrative applications have been selected. Firstly, we examine the Z dependence of basin compressibilities in the elements of the first two rows of the periodic table, and secondly, we focus our attention on the chemical changes across the pathway of the zinc blende–rocksalt phase transition in BeO.