LCAO analysis of Sr sub(2)RuO sub(4) band structure

A simple tight-binding model for the conduction band of Sr sub(2)RuO sub(4) is presented. The Ru4d sub( epsilon ) and O2p sub( pi ) orbitals of RuO sub(2) conduction plane are taken into account. In momentum representation the LCAO Hamiltonian has a block structure, containing hopping amplitudes between the in-plane orbitals O sub(a)2p sub(y), O sub(b)2p sub(x), Ru4d sub(xy), and those vertical to RuO sub(2) plane - Ru4d sub(yz), Ru4d sub(zx), O sub(a)2p sub(z) and O sub(b)2p sub(z). This simple structure allows an analytical derivation of electron band dispersions epsilon (p sub(x), p sub(y)) and constant energy contours epsilon (p sub(x), p sub(y)) identical with const. The energy surfaces epsilon (p sub(x), p sub(y)) (numerically calculated) are also related to angle-resolved photoemission spectra. Based on the analytical results a fitting philosophy for both the available experimental data and ab initio calculations is discussed. The tight-binding parameters calculated within the adopted model are found to be in acceptable agreement with the first principles calculations.