BASIC FEATURES OF THE SHORT-RANGE-ORDER MULTIPLE-SCATTERING XANES THEORY

Short-range order multiple scattering approach to study XANES spectra is considered here based on the first principle many-body X-ray absorption intensity formula beyond sudden (intrinsic) approximation. The interference effects between intrinsic and extrinsic loss of a photoelectron is explicitly taken into account and discussed in detail. One important conclusion is the suppression of the jump structure for an intrinsic loss threshold because of the subtle cancellation of these two effects. An efficient new method to treat full multiple scattering processes is developed which is based on partitioning technique. This theory allows us to treat infinite and finite multiple scattering on the same footings: We can exclude unimportant full multiple scatterings but include important full multiple scatterings.