剪切形变下掺杂及缺陷对MoS2电子结构的影响

本文利用密度泛函理论,研究剪切形变下掺杂改性及不同类型缺陷对MoS2电子结构的影响。发现：剪切形变下,MoS2+P体系为相对最稳定的结构,掺杂改性相较于缺陷对模型稳定性影响更小;模型MoS2+P+Se中P-Mo键易形成共价键,而其中的Se-Mo键和MoS2+P-Mo-S模型中的P-Mo键,易形成离子键;掺杂使MoS2模型能隙变大,而缺陷使能隙减小,且S和Mo原子共缺陷的模型带隙为0;缺陷相较于掺杂改性模型,更能使Mo原子周围增加电荷聚集度,带隙值更低,更能影响或调控模型的电子结构。     

A Sufficient Condition for Interolation by Functions in A~P(φ) (1

肖杰  赵大蕻 《数学季刊》1992,(4)

R_2Fe_17_C化合物的结构与内禀磁性的研究

本文系统研究了R_2Fe_17_C(R=Y,Sm,Gd,Tb、Dy.Er) 化合物的结构与内享磁性, 井与相应的R_2Fe_17_C 化合物进行了比较.R_2Fe_17_C 的居里温度比相应氏R_2Fe_17 的居里温度增加大约200K. 本文讨论了C 原子对该化合物结构与磁性的影响, 同时, 还对Sm_2(Fe_1-xCo_x)_17C系列化合物进行了研充. 关键词：     

400GeV/c pp碰撞赝快度空间带电粒子数密度的研究

利用CERNNA27合作组提供的LEBC泡室照片,测量了400GeV/cpp碰撞产生的带电粒子多重数为4—24的赝快度分布.观察到在选择的赝快度窗口(Δη=0.5和0.1)内平均最大带电粒子数密度随带电粒子多重数线性增加的规律.最大带电粒子数密度的几率分布在n大时有加宽和变平坦的趋势.没有观察到最大粒子数密度反常高的事例.     

红黑排序混合算法收敛速度分析

The algorithm of applying the block Gauss elimination to the Red-Black or-dering matrix to reduce the order of the system then solve the reduced system byiterative methods is called Hybrid Red-Black Ordering algorithm.In this paper,we discuss the convergence rate of the hybrid methods combined with JACOBI,CG,GMRES(m).Theoretical analysis shows that without preconditioner thesethree hybrid methods converge about 2 times as fast as the corresponding natural ordering methods.For the case that all the eigenvalues is near the real axis, the GMRES(m) algorithm converges about 3 times faster than the natural ordering GMRES(m).Various numerical experiments are presented.For large scale prob-lem with preconditioners, numerical experiments show that the GMRES(m) hybrid methods converge from about 3 times to even 5 times as fast as the natural order-ing methods and the computing time is reduced to about 1/3 even 1/6 of that of the natural ordering methods.     

Monomial bases for -Schur algebras

Using the Beilinson-Lusztig-MacPherson construction of the quantized enveloping algebra of and its associated monomial basis, we investigate -Schur algebras as ``little quantum groups". We give a presentation for and obtain a new basis for the integral -Schur algebra , which consists of certain monomials in the original generators. Finally, when , we interpret the Hecke algebra part of the monomial basis for in terms of Kazhdan-Lusztig basis elements.

     

求解非对称线性方程组的QMRGCGS方法

1 引言 求解非对称线性方程组Ax=b的双共轭梯度方法(BCG)[3]和它的变形共轭梯度平方方法(CGS)[6]都有典型的不规则收敛行为,后来Freund和Nachtigal提出一种BCG类方法,即拟极小剩余方法(QMR)[7],用来补救BCG方法的收敛性并且产生了光滑的收敛曲线。然而,象BCG方法一样,QMR方法要用到系数矩阵A及其转置A~T与向量的乘积,为了解决这一问题,Freund提出TFQMR方法,此方法具有拟极小剩余性,同时不需用到A~T与向量的乘积。     

大亚湾核电站周围大气流场监测数据同化分析

在大亚湾核电站周围大气流场分布模拟计算中,引入了一种简化的同化技术,用以解决观测数据在时间、空间上分布不均匀导致的流场预报误差.测试并分析了该同化技术对计算模式和初始场的影响,结果表明该同化方法对模式误差和初始场误差的抑制是显著的.     

Construction of the Phasing System for BEPCⅡ Linac

In order to get high beam quality, a RF distribution system is required, with minimal phase drifts and errors in the BEPCⅡ linac. The additional installation of phase reference cables and monitoring equipments and stable RF distribution for BEPC linac are finished. The master oscillator is chosen to offer RF signal with low phase noise and a stable phase distribution system is built to deliver RF signal to each klystron. A phase and amplitude detector is constructed to measure the phase precisely and an IΦA unit is used for a phase shifter. Control software based on EPICS is used to connect all the units of the system, and a phasing method based on BPM is adopted to optimize the phase of each klystron. Now the phasing system is installed and tested in the klystron gallery of the BEPCⅡ linac.     

Local Modulation of Double Electromagnetically Induced Transparency Spectrum

The double electromagnetically induced transparency induced by two coupling fields can be realized in a fourlevel tripod-type atom. Such double transparency spectra can be locally modulated by using the weak coherent fields to perturb the coupling transitions. These investigations within this scheme can be independent of Doppler broadening by properly orienting these fieds.