Resonant X-ray scattering in KCuF3

We study the resonant X-ray scattering (RXS) spectra around the Cu K edge in KCuF3 on the basis of the band structure calculation combined with the LDA+U approximation. The lattice distortion is introduced as inputs of the calculation. We reproduce well the experimental spectra as a function of photon energy around the main-K-edge (MKE). The spectral structure around the MKE is independent of the magnetic order (MO) and the orbital order (OO) but strongly dependent on the magnitude of the Jahn-Teller distortion (JTD)