Bonding changes along solid-solid phase transitions using the electron localization function approach

Abstract

Recent computational developments on the application of the Electron Localization Function in the solid state allow to perform a rich characterization of chemical changes along phase transitions induced by thermodynamic variables in crystals. Chemical entities, in the sense of the Lewis theory, can be idengified and classified according to the role they play in these processes. Covalent (SiO2), ionic (BeO), molecular (CO2, O2), and metallic (Na, K) systems have been selected to illustrate the ability of ELF to gain insight into the global understanding of the transformations. Detailed topological analysis of the bonding reconstruction process clearly distinguishes transitions where the bonding nature of the solid is not altered, and just a reorganization takes place, to those where the chemical pattern suffers a dramatic change. We have highlighted the close relationship between energy, structure and bonding across several transition pathways and how ELF can be of help to anticipate pressure induced emerging structures and to discard among competitive transition mechanism.