The influence of the size distribution of particles on the viscous property of an electrorheological fluid has been investigated by the molecular dynamic simulation method.The shear stress of the fluid is found to dec...The influence of the size distribution of particles on the viscous property of an electrorheological fluid has been investigated by the molecular dynamic simulation method.The shear stress of the fluid is found to decrease with the increase of the variance σ^(2) of the Gaussian distribution of the particle size,and then reach a steady value whenσis larger than 0.5.This phenomenon is attributed to the influence of the particle size distribution on the dynamic structural evolution in the fluid as well as the strength of the different chain-like structures formed by the particles.展开更多
The localized vibrational modes of exciton and polaron are investigated, and the results show that the frequencies of the three even parity modes of exciton are very different from those of polaron. For the exciton, t...The localized vibrational modes of exciton and polaron are investigated, and the results show that the frequencies of the three even parity modes of exciton are very different from those of polaron. For the exciton, three modes are distinctly separated;but, for the polaron, two modes with higher frequencies are close to each other, Then, it is possible to distinguish exciton from polaron by watching their Roman spectra. Therefore, the localized mode may be used to specify the exciton and polaron in the electroluminesent polymers.展开更多
Going beyond both a simple perturbative theory and Hartree-Fock treatment,the Gutzwiller variational scheme is employed to clarify the possibility of electron site-pairing in doped C_(60).It is shown that this pairing...Going beyond both a simple perturbative theory and Hartree-Fock treatment,the Gutzwiller variational scheme is employed to clarify the possibility of electron site-pairing in doped C_(60).It is shown that this pairing can be induced by electron-phonon interaction rather than electron-electron interaction.Our results are supported by EPR experiments.展开更多
A dynamical scheme is employed to simulate the self-trapping of the exciton in C_(60).During the self-trapping process,due to the bond distortion,two gap states A_(1u) and A_(2u) are separated from the highest occupie...A dynamical scheme is employed to simulate the self-trapping of the exciton in C_(60).During the self-trapping process,due to the bond distortion,two gap states A_(1u) and A_(2u) are separated from the highest occupied molecular orbital and the lowest unoccupied molecular orbital respectively.From the evolutions of the bond distortion and these two levels the relaxation time of the self-trapping exciton is about 90 fs.It is noticed that the relaxation of the exciton is much quicker than that of the charge transfer in C_(60).展开更多
The biexciton in conjugated polymers is studied in the Su-Schrieffer-Heeger model appended by a long-range Coulomb interaction.The wave function of the biexciton is constructed in the Heitler-London approach and,for t...The biexciton in conjugated polymers is studied in the Su-Schrieffer-Heeger model appended by a long-range Coulomb interaction.The wave function of the biexciton is constructed in the Heitler-London approach and,for the first time,the binding energy and radius of the biexciton in conjugated polymers is calculated.展开更多
A hydrodynamic boundary condition for the lattice Boltzmann model at impermeable boundaries is developed.This boundary condition satisfies both the no-slip condition and the fluid conservation at boundary nodes.Poiseu...A hydrodynamic boundary condition for the lattice Boltzmann model at impermeable boundaries is developed.This boundary condition satisfies both the no-slip condition and the fluid conservation at boundary nodes.Poiseuille flow and Couette flow are calculated with this technique to demonstrate the accuracy of the present boundary condition.展开更多
基金Supported by the National Natural Science Foundation of Chinathe National Education Commission under the Grant for Training Doctors.
文摘The influence of the size distribution of particles on the viscous property of an electrorheological fluid has been investigated by the molecular dynamic simulation method.The shear stress of the fluid is found to decrease with the increase of the variance σ^(2) of the Gaussian distribution of the particle size,and then reach a steady value whenσis larger than 0.5.This phenomenon is attributed to the influence of the particle size distribution on the dynamic structural evolution in the fluid as well as the strength of the different chain-like structures formed by the particles.
基金the National Natural Science Foundation of China under Grant Nos.59790050 and 19874014National Project 863-715-010the Shanghai Center of Applied Physics.
文摘The localized vibrational modes of exciton and polaron are investigated, and the results show that the frequencies of the three even parity modes of exciton are very different from those of polaron. For the exciton, three modes are distinctly separated;but, for the polaron, two modes with higher frequencies are close to each other, Then, it is possible to distinguish exciton from polaron by watching their Roman spectra. Therefore, the localized mode may be used to specify the exciton and polaron in the electroluminesent polymers.
基金Supported by the National Natural Science Foundation of China,and Advanced Material Committee of China.
文摘Going beyond both a simple perturbative theory and Hartree-Fock treatment,the Gutzwiller variational scheme is employed to clarify the possibility of electron site-pairing in doped C_(60).It is shown that this pairing can be induced by electron-phonon interaction rather than electron-electron interaction.Our results are supported by EPR experiments.
基金Supported by the National Natural Science Foundation of ChinaAdvanced Material Committee of China,rmd KOSEF 94080011013.
文摘A dynamical scheme is employed to simulate the self-trapping of the exciton in C_(60).During the self-trapping process,due to the bond distortion,two gap states A_(1u) and A_(2u) are separated from the highest occupied molecular orbital and the lowest unoccupied molecular orbital respectively.From the evolutions of the bond distortion and these two levels the relaxation time of the self-trapping exciton is about 90 fs.It is noticed that the relaxation of the exciton is much quicker than that of the charge transfer in C_(60).
基金Supported by the National Natural Science Foundation of ChinaAdvanced Materialc Committee of China.
文摘The biexciton in conjugated polymers is studied in the Su-Schrieffer-Heeger model appended by a long-range Coulomb interaction.The wave function of the biexciton is constructed in the Heitler-London approach and,for the first time,the binding energy and radius of the biexciton in conjugated polymers is calculated.
基金Supported in part by Exxon R&E company,the Chinese Postdoctoral Foundation,and ShanghaiPostdoctoral Foundation.
文摘A hydrodynamic boundary condition for the lattice Boltzmann model at impermeable boundaries is developed.This boundary condition satisfies both the no-slip condition and the fluid conservation at boundary nodes.Poiseuille flow and Couette flow are calculated with this technique to demonstrate the accuracy of the present boundary condition.
