Octahedral tilting in ACu3Ru4O12 (A=Na, Ca, Sr, La, Nd)

The perovskite-like compounds ACu₃Ru₄O₁₂ (A=Na, Ca, Sr, La, Nd) are studied by means of density functional theory based electronic structure calculations using the augmented spherical wave (ASW) method. The electronic properties are strongly influenced by covalent-type bonding between transition metal d and oxygen p states. The characteristic tilting of the RuO₆ octahedra arises mainly from the Cu–O bonding, allowing for optimal bond lengths between these two atoms. Our results provide a deeper understanding of octahedral tilting as a universal mechanism, applicable to a large variety of multinary compounds.