Journal of Synchrotron Radiation

Volume 10, Part 1 (January 2003)

research papers

J. Synchrotron Rad. (2003). 10, 43-45 [ doi:10.1107/S0909049502017223 ]

New developments in the theory and interpretation of X-ray spectra based on fast parallel calculations

J. J. Rehr and A. L. Ankudinov

Abstract: There has been dramatic progress over the past decade both in theory and in ab initio calculations of X-ray absorption fine structure. Significant progress has also been made in understanding X-ray absorption near-edge structure (XANES). This contribution briefly reviews the developments in this field leading up to the current state. One of the key advances has been the development of several ab initio codes such as FEFF, which permit an interpretation of the spectra in terms of geometrical and electronic properties of a material. Despite this progress, XANES calculations have remained challenging both to compute and to interpret. However, recent advances based on parallel Lanczos multiple-scattering algorithms have led to speed increases of typically two orders of magnitude, making fast calculations practicable. Improvements in the interpretation of near-edge structure have also been made. It is suggested that these developments can be advantageous in structural biology, e.g. in post-genomics studies of metalloproteins.

Keywords: extended X-ray absorption fine structure spectroscopy (EXAFS); X-ray absorption near-edge structure (XANES); Lanczos multiple-scattering algorithms; parallel processing.