First-principles study: Effect of relaxation on the geometrical structure of La0.5Co4Sb12

In this study, the internal parameters of La-filled skutterudite La0.5Co4Sb12 were relaxed following the damped Newton dynamic schemes. The relaxation results show that the distances and the bond lengths of atoms around the filling atom slightly change. The NN (nearest neighbor) Sb atom shows outward relaxation. Contrarily, the NNN (next nearest neighbor) Co atom and the TNN (third nearest neighbor) Sb atom show inward relaxations. The relaxation of internal parameters resulting from La filling has significant effects on the bonding charge density resulting in the change of charge distribution and bond length as well as bond angle. Based on the internal parameters after relaxation, the electronic structures of La0.5Co4Sb12 were calculated by utilizing the FLAPW (Full Potential Linear Augmented Plane Wave) based on the DFT (Density Functional Theory) of the first-principles in detail. As a comparison, the band structure of CoSb3 was calculated. The effects of La filling on the electronic structure and electrical conduction of La0.5Co4Sb12 were discussed.