First-Principles Calculations of Hydrogen Insertion Effects on Electronic Properties of TiCr2 and Ti0.875Mg0.125Cr2

TiCr2 based alloys of AB2 type with C15 Laves phase structure are good candidates for hydrogen storage. In this work, we used density functional theory and plane-wave pseudo potential technique to study electronic properties of TiCr2H3 and TiMgCr2H3. In TiCr2, the H atom interacts more strongly with the Ti than with Cr atoms and tends to occupy the g (2A2B) site; the TiCr2H3 has an insulating character. In Ti0.875Mg0.125Cr2H3, H atoms interact with both Ti atom and Mg atom, and Ti0.875Mg0.125Cr2H3 conserves its metallic character. Structural stability of TiCr2H3 and Ti0.875Mg0.125Cr2H3 is investigated by calculating their formation enthalpies. Total and partial electronic densities of states and electronic charge differences of the compounds are also computed and discussed.