An investigation of the use of the Hedin-Lundqvist exchange and correlation potential in EXAFS data analysis

In real systems, inelastic processes remove photoelectrons from the elastic scattering channel. This reduces the amplitude of the EXAFS. Traditionally the discrepancies between experimental and theoretical amplitudes were treated by including two semi-empirical reduction factors in the data analysis. Some inelastic effects may, however, be modelled more rigorously using a complex exchange and correlation potential, for example the Hedin-Lundqvist (HL) potential used in most EXAFS data-analysis programs. In this paper a systematic study of the effects of the HL potential on the calculated EXAFS amplitudes is presented. Expressions are derived whereby the EXAFS amplitudes may be examined in the presence of an arbitrary complex potential independently to the rest of the EXAFS signal. These results are used to study the effects of the HL potential on EXAFS data analysis in detail.