INELASTIC X-RAY SCATTERING INVESTIGATION OF ELECTRON CORRELATIONS IN ALUMINUM.* B. C. Larson, Oak Ridge National Laboratory (ORNL); J. Z. Tischler, ORNL; E. D. Isaacs, AT&T Bell Labs; P. Zschack, Oak Ridge Associated Universities; A. Fleszar, Universität Würzburg; and A. G. Eguiluz, University of Tennessee and ORNL.

We have made inelastic x-ray scattering measurements of the dynamical structure factor S(q,[[omega]]) for aluminum using the X-14 beam line at the National Synchrotron Light Source (NSLS); these measurements have been used to make the first large-q determination of the many-body local-field factor G(q,[[omega]]) for this simple metal. Within a Hubbard-like model, the local field-factor (LFF) provides a measure of short-range electron-electron correlations, which have been the subject of extensive theoretical interest for over forty years. Experimental information on G(q,[[omega]]) at large-q has been lacking; however, we have used ab initio calculations of the electronic-response for non-interacting electron-hole pairs [[chi]]⁽⁰⁾(q,[[omega]]), including the band structure, to extract the real and imaginary parts of the LFF directly from inelastic x-ray scattering measurements. G(q,[[omega]]) has been found to be largely real and much stronger than predicted by theory, reaching a value ~2 for q ~ 2k_F. In addition, we have observed the polarizability for non-interacting electron-hole pairs, [[chi]]⁽⁰⁾(q,[[omega]]), at the "critical" wave vector for which G(q,[[omega]]) ~ 1, and at large q, for which the effects of the electron-electron interactions become negligible. The analysis of S(q,[[omega]]) measurements made along the [013] and [001] directions for wave vectors from 0.7k_F to 2.5k_F will be discussed. RPA and [[chi]]⁽⁰⁾(q,[[omega]]) calculations will be used to illustrate the impact of long-range Coulomb interactions and short-range exchange-correlation effects on S(q,[[omega]]) as a function of wave vector.

*Research sponsored by the Division of Materials Sciences, USDOE under contract number DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp., and the National Energy Research Supercomputer Center.