Pre-K-edge structure on anomalous X-ray scattering in LaMnO3

We study the pre-it-edge structure of the resonant X-ray scattering fur for bidden reflections (anomalous scattering) in LaMnO3, using the band structu re calculation based on the local density approximation. We find a two-peak structure with an intensity approximately 1/100 that of the main peak. Thi s originates from a mixing of Ip states of Mn to 3d states of neighbouring Mn sites. The effect is enhanced by an interference with the tail of the ma in peak. The effect of the quadrupole transition is found to be one order o f magnitude smaller than that of the dipole transition. slightly modifying the azimuthal-angle dependence.