Ab initio calculation of resonant x-ray scattering in manganites - art. no. 060408

We study the origin of the resonant x-ray signal in manganites and generali ze the resonant cross section to the band-structure framework. With nb init io LSDA and LSDA + U calculations we determine the resonant x-ray spectrum of LaMnO3. The calculated spectrum and azimuthal angle dependence at the Mn K edge reproduce the measured data without adjustable parameters. The inte nsity of this signal is directly related to the orthorhombicity of the latt ice. We also predict a resonant x-ray signal at the La L edge, caused by th e tilting of the MnO6 octahedra. This shows that the resonant x-ray signal in the hard x-ray regime can be understood in terms of the band structure o f a material and is sensitive to the fine details of crystal structure.