Scattering-matrix formulation of curved-wave multiple-scattering theory: Application to x-ray-absorption fine structure

Journal Article · Sun Apr 15 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.8139· OSTI ID:6900047

Rehr, J J ^[1]; Albers, R C ^[2]

---

1. Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (USA)
2. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)

Curved-wave multiple-scattering contributions to XAFS (x-ray-absorption fine structure) are calculated with use of an efficient formalism similar to that based on the plane-wave approximation, but with scattering amplitudes {ital f}({theta}) replaced by distance-dependent scattering matrices'' {ital F}{sub {lambda},{lambda}{prime}}({rho},{rho}{prime}). Here {rho}={ital k}{bold R}, {ital k} being the photoelectron wave number and {bold R} is a bond vector, while the matrix indices {lambda}=({mu},{nu}) represent terms in a convergent expansion that generalizes the small-atom approximation. This approach is based on an exact, separable representation of the free propagator (or translation operator) matrix elements, {ital G}{sub {ital L},{ital L{prime}}}({ital k}{bold R}), in an angular momentum {ital L}=({ital l},{ital m}) and site basis. The method yields accurate curved-wave contributions for arbitrarily high-order multiple-scattering paths at all positive energies, including the near-edge region. Results are nearly converged when the intermediate {lambda} summations are truncated at just six terms, i.e., (6{times}6) matrices. The lowest-order (1{times}1) matrix {ital F}{sub 00,00} is the effective, curved-wave scattering amplitude, {ital f}({rho},{rho}{prime},{theta}), and yields a multiple-scattering expansion equivalent to the point-scattering approximation. Formulas for multiple-scattering contributions to XAFS and photoelectron diffraction are presented, and the method is illustrated with results for selected multiple-scattering paths in fcc Cu.

• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6900047
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 41:12; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER
X-RAY SPECTROSCOPY
FINE STRUCTURE
MULTIPLE SCATTERING
ABSORPTION SPECTROSCOPY
BORN APPROXIMATION
ELEMENTS
METALS
SCATTERING
SPECTROSCOPY
TRANSITION ELEMENTS
656002* - Condensed Matter Physics- General Techniques in Condensed Matter- (1987-)