The soliton perturbations for the combined Korteweg de Vries and modified Korteweg de Vries(KdV-MKdV)equation are studied.The first-order effects of perturbation on a soliton,namely both the slow time-dependence of th...The soliton perturbations for the combined Korteweg de Vries and modified Korteweg de Vries(KdV-MKdV)equation are studied.The first-order effects of perturbation on a soliton,namely both the slow time-dependence of the soliton parameters and the first-order correction are derived through constructing the appropriate Green's function.展开更多
We investigate theoretically the spin current in a quantum wire with weak Dresselhaus spin-orbit coupling connected to two normal conductors. Both the quantum wire and conductors are described by a hard-wall confining...We investigate theoretically the spin current in a quantum wire with weak Dresselhaus spin-orbit coupling connected to two normal conductors. Both the quantum wire and conductors are described by a hard-wall confining potential. Using the electron wave-functions in the quantum wire and a new definition of spin current, we have calculated the elements of linear spin current density j^Ts,xi and j^Ts,yi（i=x, y, z）. We find that the elements j^Ts,xx and j^Ts,yy have a antisymmetrical relation and the element j^Ts,yz has the same amount levelas j^Ts,xx and j^Ts,yy. We also find a net linear spin current density, which has peaks at the center of quantum wire. The net linear spin current can induce a linear electric field, which may imply a way of spin current detection.展开更多
We investigate theoretically the spin accumulation in a Rashba spin-orbit coupling (SOC) nanoribbon nonadiabatically connected to a normal conductor.Both the nanoribbon and conductor are described by a hard-wall confi...We investigate theoretically the spin accumulation in a Rashba spin-orbit coupling (SOC) nanoribbon nonadiabatically connected to a normal conductor.Both the nanoribbon and conductor are described by a hard-wall confining potential.Using the scattering matrix approach within the effective free-electron approximation,we have calculated the out-of-plane spin accumulation in the nanoribbon.It is found that the spin accumulation shifts toward the two edges of nanoribbon with the increasing of propagation modes.Specifically,as the Rashba SOC strength increases the spin accumulation in the nanoribbon will be enhanced and this result may suggest us a simple method to control the spin accumulation of the system by Rashba SOC strength.展开更多
We numerically study the intrinsic localized vibrational modes in a diatomic chain with different masses and alternating force constants between nearest neighbors.This model simulates a row of atoms in the<111>d...We numerically study the intrinsic localized vibrational modes in a diatomic chain with different masses and alternating force constants between nearest neighbors.This model simulates a row of atoms in the<111>direction of sphalerite-structure crystal.We found that the harmonic and quartic anharmonic terms in the nearest-neighbor interaction potential produce the intrinsic localized modes with frequencies above the optical branch or in the gap of the linear spectrum,the distribution patterns of atom amplitudes are asymmetry with a form of quasi-even-or quasi-odd-parity,and the inclusion of cubic term in the potential lowers the frequencies of the modes and introduces static displacements for the atoms.展开更多
A new direct approach based on the Fourier transformation is developed and applied to study the perturbed sine-Gordon equation.Since a new basis for perturbation expansion is introduced,the first-order correction is e...A new direct approach based on the Fourier transformation is developed and applied to study the perturbed sine-Gordon equation.Since a new basis for perturbation expansion is introduced,the first-order correction is expressed in terms of Bessell functions.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19775013.
文摘The soliton perturbations for the combined Korteweg de Vries and modified Korteweg de Vries(KdV-MKdV)equation are studied.The first-order effects of perturbation on a soliton,namely both the slow time-dependence of the soliton parameters and the first-order correction are derived through constructing the appropriate Green's function.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20060542002the Hunan Provincial Natural Science Foundation of China under Grant No.06JJ2097the Hunan College of Science and Technology Research Foundation of China under Grant No.07XKYTB001
文摘We investigate theoretically the spin current in a quantum wire with weak Dresselhaus spin-orbit coupling connected to two normal conductors. Both the quantum wire and conductors are described by a hard-wall confining potential. Using the electron wave-functions in the quantum wire and a new definition of spin current, we have calculated the elements of linear spin current density j^Ts,xi and j^Ts,yi（i=x, y, z）. We find that the elements j^Ts,xx and j^Ts,yy have a antisymmetrical relation and the element j^Ts,yz has the same amount levelas j^Ts,xx and j^Ts,yy. We also find a net linear spin current density, which has peaks at the center of quantum wire. The net linear spin current can induce a linear electric field, which may imply a way of spin current detection.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20060542002the Hunan Provincial Natural Science Foundation of China under Grant No.06JJ2097the Hunan University of Science and Engineering Research Foundation of China under Grant No.07XKYTB001
文摘We investigate theoretically the spin accumulation in a Rashba spin-orbit coupling (SOC) nanoribbon nonadiabatically connected to a normal conductor.Both the nanoribbon and conductor are described by a hard-wall confining potential.Using the scattering matrix approach within the effective free-electron approximation,we have calculated the out-of-plane spin accumulation in the nanoribbon.It is found that the spin accumulation shifts toward the two edges of nanoribbon with the increasing of propagation modes.Specifically,as the Rashba SOC strength increases the spin accumulation in the nanoribbon will be enhanced and this result may suggest us a simple method to control the spin accumulation of the system by Rashba SOC strength.
基金Supported by the National Nature Science Foundation of China under Grant No.19975013by the Science Foundation of Hunan Education Commission under Grant No.301566.
文摘We numerically study the intrinsic localized vibrational modes in a diatomic chain with different masses and alternating force constants between nearest neighbors.This model simulates a row of atoms in the<111>direction of sphalerite-structure crystal.We found that the harmonic and quartic anharmonic terms in the nearest-neighbor interaction potential produce the intrinsic localized modes with frequencies above the optical branch or in the gap of the linear spectrum,the distribution patterns of atom amplitudes are asymmetry with a form of quasi-even-or quasi-odd-parity,and the inclusion of cubic term in the potential lowers the frequencies of the modes and introduces static displacements for the atoms.
基金Supported by the National Natural Science Foundation of China under Grant No.19775013.
文摘A new direct approach based on the Fourier transformation is developed and applied to study the perturbed sine-Gordon equation.Since a new basis for perturbation expansion is introduced,the first-order correction is expressed in terms of Bessell functions.
