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61.
The electronic structure and magnetic properties of the Ti2CoB Heusler compound with a high-ordered CuHg2Ti structure were investigated using the self-consistent full potential linearized augmented plane wave (FPLAPW) method within the density functional theory (DFT). Spin-polarized calculations show that the Ti2CoB compound is half-metallic ferromagnetic with a magnetic moment of 2 μB at the equilibrium lattice constant, a=5.74 Å. The Ti2CoB Heusler compound is ferromagnetic below the equilibrium lattice constant and ferrimagnetic above the equilibrium lattice constant. A large peak in majority-spin DOS and an energy gap in minority-spin DOS are observed at the Fermi level, yielding a spin polarization of 100%. A spin polarization higher than 90% is achieved for a wide range of lattice constants between 5.6 and 6.0 Å. 相似文献
62.
In this paper, we study the polynomial integrability of natural Hamiltonian systems with two degrees of freedom having a homogeneous potential of degree k given either by a polynomial, or by an inverse of a polynomial. For k=−2,−1,…,3,4, their polynomial integrability has been characterized. Here, we have two main results. First, we characterize the polynomial integrability of those Hamiltonian systems with homogeneous potential of degree −3. Second, we extend a relation between the nontrivial eigenvalues of the Hessian of the potential calculated at a Darboux point to a family of Hamiltonian systems with potentials given by an inverse of a homogeneous polynomial. This relation was known for such Hamiltonian systems with homogeneous polynomial potentials. Finally, we present three open problems related with the polynomial integrability of Hamiltonian systems with a rational potential. 相似文献
63.
Hailin LiuZhihong Lu ling YueJing Liu Zhanghua GanChang Shu Ting ZhangJing Shi Rui Xiong 《Applied Surface Science》2011,257(22):9355-9361
A series of Ti1−xMoxO2−yNy samples were prepared by using sol-gel method and characterized by X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. All Ti1−xMoxO2−yNy samples are anatase phase. It is found that Mo, N mono-doping can increase visible light absorption, while (Mo + N) co-doping can greatly enhance absorption in whole visible region. Results of our first-principles band structure calculations reveal that (Mo + N)-doping, especially passivated co-doping can increase the up-limit of dopant concentration and create more impurity bands in the band gap of TiO2, which leads to a greatly increase of its visible-light absorption without a decrease of its redox potential. It reveals that (Mo + N) co-doped TiO2 is promising for a photocatalyst with high photocalystic activity under visible light. 相似文献
64.
With the progress of LSI technology, the electronic device size is scaled down to the sub 0.1μ m region. In such an ultrasmall device, it is indispensable to take quantum mechanical effects into account in device modeling. In this paper, we present a newly developed quantum Monte Carlo device simulation applicable to ultrasmall semiconductor devices. In this model, the quantum effects are represented in terms of quantum mechanically corrected potential in the classical Boltzmann equation. It is demonstrated that the quantum transport effects such as tunneling and energy quantization in ultrasmall semiconductor devices are obtained for the first time by using the standard Monte Carlo techniques. 相似文献
65.
Experiments with heavy ions at moderate energies show the importance of deformation in heavy ion collisions. A deformation
model which takes deformation dynamically into account is developed. Having described fusion and deep inelastic collision
for a very heavy system (Xe + Bi) and a medium heavy system (Ar + Th) at various energies successfully, we turn to some comparatively
lighter heavy ions where fusion is the most dominant feature. Fusion cross-sections for six pairs of lighter systems (35Cl +116Sn,58Ni+62Ni,35Cl+62Ni,32S+24Mg,24Mg+24Mg and12C+27Al) have been obtained using our deformation model which agree well with experiment. The two-slope-behaviour of fusion excitation
function which is an important feature of light ion fusion systematics is also obtained, in our model calculations for all
the systems studied. 相似文献
66.
R. Syski 《Stochastic Processes and their Applications》1977,5(2):93-129
A Markov chain (with a discrete state space and a continuous parameter) is perturbed by forcing a chain to return to “permissible” states whenever it happens to enter “forbidden” states, with returns governed by a replacement distribution.The compensation method is employed to obtain the distribution for the modified chain, in terms of the original chain and the perturbation mechanism.Emphasis is placed on ergodic chains, and interpretation of results in terms of perturbation theory of semi-groups and the ergodic potential theory (based on the fundamental matrix of a chain) is mentioned. 相似文献
67.
A theoretical investigation of 1D stationary and transient quasi-periodical dielectric structures is presented. A new approach for solving the problem of field interaction with such structures common for both stationary and transient cases, based on integral equations for the fields in transient media, is proposed. Some special cases of quasi-periodical structures with doubled quasi-periodicity are investigated numerically, showing that an additional complexity of the structure allows to obtain good filtering properties with a small number of quasi-periods. Transient structures with the same spatial dependencies, but with a time-dependent permittivity were also investigated. 相似文献
68.
We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio. 相似文献
69.
Wang-Quan He Can-Jun Wang Dong-Cheng Mei 《International Journal of Theoretical Physics》2008,47(6):1606-1611
We investigate the noise-induced transport of Brownian particle in a deterministic spatial symmetrical periodic potential
driven by colored cross correlation between a multiplicative white noise and an additive white noise. We derive the general
formula of the stationary current. Based on numerical computation, we found that directed motion of the Brownian particles
can be induced by the correlation time τ of cross correlation between the multiplicative noise and the additive noise and the current reversal and the direction of
the current is controlled by the τ. 相似文献
70.
Nonlinear wave propagation is studied theoretically in a one-dimensional photonic band gap structure containing single negative materials. It is found that Kerr nonlinearity is greatly enhanced near the lower edge of a recently explored angular gap for transverse magnetic polarized light. Consequently, optical bistability is achieved at very low values of input intensity in a periodic structure composed of only a few repeating units. The characteristics of optical bistability are affected only slightly with the variation of the incident angle and thickness ratio of the layers. The effect of losses is also found to be relatively insignificant in such a small structure. 相似文献