Real-space multiple-scattering approach to XANES

The historical development of ideas in x-ray absorption and multiple scattering theory that lead to real space, multiple scattering (RSMS) calculations of XANES is reviewed. The RSMS method for both XANES and electronic structure calculations has several advantages with respect to other approaches. Recently developed RSMS codes now provide a way to interpret XANES in terms of structural and electronic information. The sensitivity of XANES calculations to muffin-tin potential construction, self-consistency and self-energy is demonstrated for the Ti K edge of PbTiO3. Future RSMS electronic structure codes require several improvements, such as non-spherical potentials and inclusion of many body effects in order to achieve more quantitative agreement with experiment.