Electronic structure and chemical bonding of α- and β-Ta₄AlC₃phases: Full-potential calculation

First-principles total-energy and heat of formation calculations on α and β polymorphs of Ta₄AlC₃have been made with a full-potential electronic structure program with the generalized gradient approximation, which shows that α phase is more stable than β phase. The charge transfer and chemical bonding of the two phases were investigated quantitatively by using Bader’s quantum theory of atoms in molecules (AIM). The results show that the bonding between Ta1-C2 is stronger in α phase than β phase, which leads to the stability of α phase.