Operator Factorization forMultiple-Scattering Problems and an Application to Periodic Media

This work concerns multiple-scattering problems for time-harmonic equations in a reference genericmedia.We consider scatterers that can be sources,obstacles or compact perturbations of the reference media.Our aim is to restrict the computational domain to small compact domains containing the scatterers.We use Robin-to-Robin(RtR)operators(in the most general case)to express boundary conditions for the interior problem.We show that one can always factorize the RtR map using only operators defined using single-scatterer problems.This factorization is based on a decomposition of the diffracted field,on thewhole domainwhere it is defined.Assuming that there exists a good method for solving single-scatterer problems,it then gives a convenient way to compute RtR maps for a random number of scatterers.

Elastic Wave Scattering by Two-Dimensional Periodical Array of Cylinders

We extend the multiple-scattering theory (MST) for elastic wave scattering and propagating in two-dimensional composite. The formalism for the band structure calculation is presented by taking into account the full vector character of the elastic wave. As a demonstration of application of the formalism we calculate the band structure of elastic wave propagating in a two-dimensional periodic arrangement of cylinders. The results manifest that the MST shows great promise in complementing the plane-wave (PW) approach for the study of elastic wave.

A theoretical study of the oxygen K-edge near-edge X-ray absorption fine structure of N_2O/Ir(110)

A multiple-scattering chtster method is employed to calculate the oxygen K-edge near-edge X-ray absorption fine structure of N20/Ir（110） and its monolayer. Two peaks and one weak resonance appear in both cases. The self- consistent field DV-Xa calculations of the peaks and resonance show that the physical origin of the pre-edge peak x is different from those of the main peak 1 and the other weak resonance al. This setup is intrinsic to the N20 monolayer, owing to the interaction between the neighbouring molecular chains in the monolayer and partly to the adsorbed atomic oxygen, according to both the theoretical and experimental data.

Monte Carlo simulation of the electromagnetic wave propagation in the duststorm

Monte Carlo simulations of the extinction rate of electromagnetic wave propagation in the duststorm were presented. The numerical procedure was based on the multiple scattering and independent scattering. The calculated multiple scattering attenuation rate is in good agreement with the measured one,but differs significantly from those obtained under the independent scattering assumption. At the same time,the factors of size parameter,frequency of incident wave,the angle of incident,and sands permittivity and water content have been considered in the attenuation of electromagnetic wave propagation in the duststorm. Numerical results obtained showed that the attenuation rate increases as the fractional volume,frequency of incident wave and sands permittivity increase,and as the angle of incident increases,the attenuation rate decreases.

DETERMINATION OF MOLECULAR BONDLENGTH BY σ~*-RESONANCE POSITION

Recently near-edge X-ray absorption fine structure (NEXAFS) has become an important method for surface structure analysing because it offers the information of intramolecular bond-length and molecular orientation for molecule adsorbate-substrate systems.