共查询到20条相似文献,搜索用时 250 毫秒
1.
本文用多时标微扰论方法分析非平衡电离问题。决定电子束缚态平均占据概率Pn的各物理过程通常具有很不相同的时间尺度。在本文中,两个相邻能级之间的跃迁过程被看作是快过程,其他过程(包括电离)则被看成是慢过程。这一理论特别适合于高Z元素的较低的束缚能级。理论给出了Pn作为自由电子数ne的近似解析表达式,结果代替求解dPn/dt方程组,只解ne的常微分方程就够了。这样,问题既得到简化又避免了dPn
关键词: 相似文献
2.
采用密度泛函理论中的广义梯度近似(DFT/GGA)方法,在PW91/DNP水平上研究了4,7-二(2-噻吩基)苯并噻二唑-3-辛基噻吩二炔(简称P)的低聚合物Pn(n=1~5)的稳定性和化学活性.结果表明:随着聚合度增加,Pn的稳定性降低,化学活性增强.采用密度泛函理论与周期性平板模型相结合的方法,研究了化合物P在TiO2(100)表面的吸附,通过吸附前后化合物P的Mulliken charge和前线轨道分析表明:当P吸附在TiO2(100)表面时,P向TiO2(100)表面转移0.692 e电荷,前线轨道能隙变窄.通过吸附前后TiO2(100)表面的能带和态密度分析表明:在TiO2(100)表面吸附了化合物P后,能带向低能区移动,且TiO2中价带和导带间的禁带消失.理论预测的结果与实验值吻合. 相似文献
3.
本文对多组元轴对称环形等离子体系统,用模型碰撞算符及Rosenbluth和Glasser发展了的变分原理,导出了满足动力学要求的新经典定标关系。在这些定标关系的基础上,给出了用组元参数nj,mj,Zj和Tj表征的多组元系统新经典流的显式。最后,详细地研究了输运系数与环状比R/a的关系。
关键词: 相似文献
4.
用渐近展开方法,给出和讨论辐射传输问题的P2近似扩散方程,并进行了数值模拟计算。结果表明,P2扩散方法优于普通扩散和限流扩散方法,其数值结果与输运方程结果十分接近。 相似文献
5.
为实现SPH二阶粒子近似,讨论光滑函数应满足的充分条件,给出对应的光滑函数形式,分析二阶粒子近似解的唯一性,并进行数值验证.结果表明:和标准SPH方法相比,在周期边界条件下,随着粒子数加密,SPH方法二阶粒子近似的L1误差减小且L1阶趋近2.0. 相似文献
6.
Interface Width Effect on the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Interface width effect on the spherical Rayleigh–Taylor instability in the weakly nonlinear regime is studied by numerical simulations.For Legendre perturbation mode Pn with wave number Kn and interface half-width L,the commonly adopted empirical linear growth rate formula γnem(L)=γn/√1 + KnL is found to be sufficient in spherical geometry.At the weakly nonlinear stage,the interface width affects the mode coupling processes.The development o... 相似文献
7.
8.
目前还没有关于PuH3的分子结构和分子光谱公开解密的资料与数据.基于密度泛函理论的全数值自洽场计算方法——离散变分方法(DVM),数值解相对论Dirac方程,在自由的钚原子和氢原子波函数的数值基及原子能级基础上计算了PuH3分子的不同几何结构及势能曲线.等边三角棱锥形PuH3分子基态的数据为:Pu-H键长=2.097726Å,键角θ(H-Pu-H)=119.102Å,H-H距离为3.616817Å,轨道总能量为-19869.834a.u.,费米能级Ef=-16.856eV.分析了反演对称等价的分子态以及非质心坐标对轨道总能量的影响.比较了PuH2和PuH3分子参数的全电子计算结果. 相似文献
9.
本文对具有特定横向弛豫时间(T2)的硫酸铜溶液进行了多回波间隔(TE)的核磁共振(NMR)实验,并利用数值模拟对32组具有不同弛豫分量的模型进行了变TE模拟实验,定量研究了TE对致密油气、页岩气等低孔低渗储层NMR孔隙度的影响规律.实验结果表明,随着TE的增大,各T2弛豫组分NMR孔隙度先维持在100%左右,然后迅速衰减,当TE增加到一定数值时,趋近于0;不同T2弛豫组分NMR孔隙度开始迅速衰减及最后变为0的TE值存在显著差异.根据不同T2弛豫组分NMR孔隙度与TE的关系,将整个NMR测量分为无损测量区、快速衰减区、无效参数区和仪器盲区4个区域.对特定弛豫组分而言,在快速衰减区弛豫组分损失量与TE呈对数关系,本文还给出了该区域NMR孔隙度的校正公式及方法. 相似文献
10.
11.
The formalism to describe electron scattering reactions on two-neutron halo nuclei is developed. The halo nucleus is described as a three-body system (core +n + n), and the wave function is obtained by solving the Faddeev equations in coordinate space. We discuss elastic and quasielastic scattering using the impulse approximation to describe the reaction mechanism. We apply the method to investigate the case of electron scattering on 6He. Spectral functions, response functions, and differential cross sections are calculated for both neutron knockout and knockout by the electron. 相似文献
12.
The Anderson hamiltonian has been studied for arbitrarily filled bands using the real space renormalization group (RSRG) method. The ground state energy is determined in one dimension for the scale factors ns = 3 and ns = 5. Direct application of RSRG gives, for a certain ns, the results for only ns number of discrete cases of band-filling. We then devise an interpolation scheme which spans the entire region of the band and gives the ground state energy for any general filling. The results, as provided by our scheme, satisfy the desired particle-hole symmetry exactly and are always an upper bound to the exact one. The non-linear dependence of the band energy on its filling is represented correctly, even for small ns. Finally, we discuss how the results improve for large ns. 相似文献
13.
We calculated the universal scaling function g(x) and the scaling factor a as well as the convergence rate δ for perlodtripling, -quadrapling and-quintuplingLseguences of RL, RL2, RLR2, RL2R and RL3 types. The superstable periods are closely connected. to a set of polynomial Pn defined recursivcely by the original mapping. Some not able properties of these polynomials are studied. Several approaches to solving the renormalization group equation and estimating the scaling factors are suggested. 相似文献
14.
15.
In this paper we study isotropic integrable systems based on the braid-monoid algebra. These systems constitute a large family of rational multistate vertex models and are realized in terms of the Bn, Cnand Dn Lie algebra and by the superalgebra Osp(n||2m). We present a unified formulation of the quantum inverse scattering method for many of these lattice models. The appropriate fundamental commutation rules are found, allowing us to construct the eigenvectors and the eigenvaluesof the transfer matrix associated to the Bn, Cn, Dn, Osp(2nt-1||2), Osp(2||2nt-2), Osp(2nt-2||2) and Osp(1||2n) models. The corresponding Bethe ansatz equations can be formulated in terms of the root structure of the underlying algebra. 相似文献
16.
17.
We consider the massless tricritical Ising model
perturbed by the thermal operator 1,3 in a cylindrical geometry and apply integrable boundary conditions, labelled by the Kac labels (r,s), that are natural off-critical perturbations of known conformal boundary conditions. We derive massless thermodynamic Bethe ansatz (TBA) equations for all excitations by solving, in the continuum scaling limit, the TBA functional equation satisfied by the double-row transfer matrices of the A4 lattice model of Andrews, Baxter and Forrester (ABF) in Regime IV. The resulting TBA equations describe the massless renormalization group flow from the tricritical to critical Ising model. As in the massive case of Part I, the excitations are completely classified in terms of (m,n) systems but the string content changes by one of three mechanisms along the flow. Using generalized q-Vandermonde identities, we show that this leads to a flow from tricritical to critical Ising characters. The excited TBA equations are solved numerically to follow the continuous flows from the UV to the IR conformal fixed points. 相似文献
18.
本文对文[1]中提出的二维长波方程给出了数值求解方法。由于此方法无需处理边界上的积分,不仅使数值计算的数据准备工作量大大减少,缩短了计算时间,降低了计算误差,而且没出现文[2]提到的短波长噪音干扰。用本文建立的方法,计算了我国渤海的M2分潮,计算结果与实测结果吻合较好。 相似文献
19.
系统描述了EV共聚物序列中两种结构因素对共聚物主链中亚甲基和次甲基13C NMR化学位移的贡献,将SCS方法与半经验方法结合起来,阐明了常数项δLE和δ0的物理意义,提出了以聚乙烯链反式构象化学位移δt为基准计算上述亚甲基和次甲基化学位移的公式:δc=δt+ΣniSi+ΣPjγj并在此基础上,讨论了聚乙烯,聚丙烯的特殊情况和乙丙共聚物的链结构. 相似文献
20.
We investigate the internal dynamics of the spinor Bose–Einstein condensates subject to dissipation by solving the Lindblad master equation. It is shown that for the condensates without dissipation its dynamics always evolve along a specific orbital in the phase space of(n_0, θ) and display three kinds of dynamical properties including Josephson-like oscillation, self-trapping-like oscillation, and ‘running phase'. In contrast, the condensates subject to dissipation will not evolve along the specific dynamical orbital. If component-1 and component-(-1) dissipate at different rates, the magnetization m will not conserve and the system transits between different dynamical regions. The dynamical properties can be exhibited in the phase space of(n_0, θ, m). 相似文献