From ELF to Compressibility in Solids

Abstract

Understanding the electronic nature of materials’ compressibility has alwaysbeen a major issue behind tabulation and rationalization of bulk moduli. This is especiallybecause this understanding is one of the main approaches to the design and proposal of newmaterials with a desired (e.g., ultralow) compressibility. It is well recognized that the softestpart of the solid will be the one responsible for its compression at the first place. In chemicalterms, this means that the valence will suffer the main consequences of pressurization.It is desirable to understand this response to pressure in terms of the valence properties(charge, volume, etc.). One of the possible approaches is to consider models of electronicseparability, such as the bond charge model (BCM), which provides insight into the cohesionof covalent crystals in analogy with the classical ionic model. However, this model relies onempirical parametrization of bond and lone pair properties. In this contribution, we havecoupled electron localization function (ELF) ab initio data with the bond charge modeldeveloped by Parr in order to analyze solid state compressibility from first principles andmoreover, to derive general trends and shed light upon superhard behavior.

Keywords

• ELF
• compressibility
• energy models