Extended Huckel tight-binding calculations of the electronic structure of YbFe₄Sb₁₂, UFe₄P₁₂, and ThFe₄P₁₂

Calculation of the band structure, total and projected density of states, crystal orbital population analysis (COOP), and Mulliken population analysis were performed for the filled skutterudites YbFe₄Sb₁₂, UFe₄P₁₂, and ThFe₄P₁₂. The calculated energy bands depict a semimetal behavior for YbFe₄Sb₁₂ and UFe₄P₁₂, and metallic behavior for ThFe₄P₁₂. Furthermore, the contributions from each orbital to the total DOS for each compound corroborate these findings. The bonding strength was derived from the COOP analysis between different pairs of atoms, considering nearest neighbor distances between 3.40 and 6.47 Å for YbFe₄Sb₁₂, 2.91 and 6.47 Å for UFe₄P₁₂, and 2.48 and 5.51 Å for ThFe₄P₁₂. Mulliken population analysis suggests ionic behavior for these compounds.