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

The perovskite-like compounds ACu(3)Ru(4)O(12) (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. (C) 2003 Elsevier Science B.V. All rights reserved.