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 t...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.展开更多
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 ...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.展开更多
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 calculat...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.展开更多
A cluster model is used to calculate electron energy-loss fine structures in crystal. The multiple-scattering self-consistent-field method is employed in the calculation. Our theoretical results of N near K-edge energ...A cluster model is used to calculate electron energy-loss fine structures in crystal. The multiple-scattering self-consistent-field method is employed in the calculation. Our theoretical results of N near K-edge energy loss fine structures in hexagonal GaN crystal are in good agreement with the experimental spectra. Future possible experiments in energy-filtered transmission electron microscopy (EFTEM) are discussed and proposed because our theoretical work can provide clear assignments for transmitted electrons with different energy losses.展开更多
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 ...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.展开更多
文摘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.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10904134 and 10802083)
文摘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.
基金the Key Project of the National Natural Science Foundation of China (Grant No. 10532040)
文摘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.
基金the National Natural Science Foundation of China ( Grant Nos.19874035, 59831020, 19734030), National 973 Project, National 863 Program, Climbing Project, The Ministry of Science and Technology of China, National High-Tec ICF Committee, the Ministry of
文摘A cluster model is used to calculate electron energy-loss fine structures in crystal. The multiple-scattering self-consistent-field method is employed in the calculation. Our theoretical results of N near K-edge energy loss fine structures in hexagonal GaN crystal are in good agreement with the experimental spectra. Future possible experiments in energy-filtered transmission electron microscopy (EFTEM) are discussed and proposed because our theoretical work can provide clear assignments for transmitted electrons with different energy losses.
基金Project supported by the National Natural Science Foundation of China.
文摘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.