Effects of charge on the structures and spin moments of Nil3 cluster

The structural stability and magnetic properties of the icosahedral Ni13, Ni13^＋1 and Ni13^-1 clusters have been obtained by utilizing all-electron density functional theory with the generalized gradient approximations for the exchange-correlation energy. The calculated results show that the ground states of neutral and charged clusters all favour a D3d structure, a distorted icosahedron, due to the Jahn-Teller effect. The radial distortions caused by doping one electron and by doping one hole are opposite to each other. Doping one electron will result in a 1/2 decrease and doping one hole will result in a 1/2 increase of the total spin. Both increasing interatomic spacing and decreasing coordination will lead to an enhancement of the spin magnetic moments for Nil3 clusters.     

钙原子4p_(1/2,3/2)ng(J=3)自电离Rydberg光谱的研究

利用Monte Carlo(MC)方法模拟研究了薄膜生长的初始阶段岛的形貌和岛的尺寸与基底温度和入射粒子剩余能量之间的关系.模型中考虑了粒子的沉积、吸附粒子的扩散和蒸发等过程.结果表明当基底温度从200K变化到260K时,岛的形貌经历了一个从分散生长逐渐过渡到分形生长的过程,并且在较低温度(200K)下,随入射粒子剩余能量的增加,岛的形貌也经历了同样的变化过程.进一步研究证明,随着基底温度的升高或入射粒子剩余能量的增加,沉积粒子的扩散能力显著增强,从而使岛的形貌发生了改变.     

Binding Energies of Excitons in Square Quantum-Well Wires in the Presence of a Magnetic Field

The binding energies of the ground state of excitons in the GaAs/Ga1-xAlxAs square quantum-well wire in the presence of a magnetic field are investigated by using the variational method. It is assumed that the magnetic field is applied parallel to the axis of the wire. The calculations of the binding energy as a fimction of the wire size have been performed for infinite and finite confinement potentials. The contribution of the magnetic field makes the binding energy larger obviously, particularly for the wide wire, and the magnetic field is much more pronounced for the binding energy in a square quantum wire than that in a cylindrical quantum wire. The mismatch of effective masses between the well and the barrier is also considered in the calculation.     

钉扎效应对聚噻吩中双空穴极化子附近局域振动模的影响

基于扩展的二维Su-Schrieffer-Heeger模型，研究了库仑钉扎作用对聚噻吩中双空穴极化子 附近的局域振动模的影响.除了与激发方式无关的本征振动模外，发现了与激发方式相关的 声子振动模式.计算结果与聚噻吩红外和拉曼光谱实验数据相当符合，从而对掺杂诱导和光 致激发下聚噻吩吸收光谱的区别给出了较好的理论阐释. 关键词： 聚噻吩 钉扎效应 吸收光谱 局域振动模     

内嵌镧原子的磁性硅纳米线的第一性原理研究

基于密度泛函理论,系统研究了由两个La@Si_(16)组装而成的高度稳定的管状二聚体La_2@Si_(32)团簇.电子结构分析显示,内嵌La原子诱导的类sp~2杂化对于提高管状Si_(32)的稳定性至关重要.Mülliken布局分析显示,La_2@Si_(32)的总磁矩为2 μ_B,主要来源于两个La原子和第三、第六层的八个Si原子;电荷是由Si原子转移到了La原子上.此外,通过连接一系列La_2@Si_(32)单体而获得了一类组装的硅纳米线La@SiNW,研究结果显示La@SiNW具有金属导电特性,其总磁矩为2 μ_B.上述特征暗示具有磁性的La_2@Si_(32)和La@SiNW可能在自旋电子器件和高密度磁记录材料方面具有潜在的应用前景.     

Stability of small Ni-Ti bimetallic clusters studied by density functional theory

The low-energy structures and the electronic and the magnetic properties of small NiNiNi$_{m}$Ti$_{n}$ clusters, lowest-energy structure, electronic and magnetic propertiesProject supported by the National Natural Science Foundation of China (Grant No.~10874039), and the Natural Science Foundation of Hebei Province of China (Grant Nos.~A2009000246 and 2009000243).3120A, 3640B, 2110K7/3/2009 12:00:00 AMThe low-energy structures and the electronic and the magnetic properties of small NiNiNi$_{m}$Ti$_{n}$ clusters, lowest-energy structure, electronic and magnetic propertiesProject supported by the National Natural Science Foundation of China (Grant No.~10874039), and the Natural Science Foundation of Hebei Province of China (Grant Nos.~A2009000246 and 2009000243).3120A, 3640B, 2110K7/3/2009 12:00:00 AMThe low-energy structures and the electronic and the magnetic properties of small Ni$_{n}$Ti$_{n}$ ($n=1$--$6$) and Ni$_{m}$Ti$_{n}$ ($1 \le n \le 4$, $1 \le m \le 4$, $n \ne m$) clusters are investigated by performing all-electron calculations based on density functional theory. Ground states and several isomers near the ground states are determined for these clusters. The results indicate that the growth of small Ni$_{m}$Ti$_{n}$ clusters prefers to form rich Ti--Ni and Ti--Ti bonds. When the percentage of titanium atoms is significantly greater than that of nickel atoms, the nickel atoms are most frequently found above the surface; in contrast, the titanium atoms prefer the bridging sites. A M\"{u}lliken spin population analysis indicates that the total spin of titanium-nickel clusters is not always zero.http://cpb.iphy.ac.cn/CN/10.1088/1674-1056/19/4/043102https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=111644NimTin;clusters;lowest-energy;structure;electronic;and;magnetic;propertiesThe low-energy structures and the electronic and the magnetic properties of small Nin Tin(n = 1-6) and Ni m Ti n(1 ≤ n ≤ 4,1 ≤ m ≤ 4,n ≠ m) clusters are investigated by performing all-electron calculations based on density functional theory.Ground states and several isomers near the ground states are determined for these clusters.The results indicate that the growth of small Ni m Ti n clusters prefers to form rich Ti-Ni and Ti-Ti bonds.When the percentage of titanium atoms is significantly greater than that of nickel atoms,the nickel atoms are most frequently found above the surface;in contrast,the titanium atoms prefer the bridging sites.A Mu¨lliken spin population analysis indicates that the total spin of titanium-nickel clusters is not always zero.     

金基纳米管AunSi12 (n=25-60)的奇异结构与电磁特性预测

应用相对论效应的密度泛函理论,系统研究了一系列稳定的中空类管状Au_nSi₁₂(n=25, 30, 35, 40, 45, 50, 55, 60)团簇. Au_nSi₁₂可以通过在不同长度的单壁Au纳米管(5, 5)的两端戴帽由二十面体Au₂₀Si₁₂平分的两个相同半球构建而成.计算结果显示,Si原子的掺杂使得Au_nSi₁₂的结构变得更加紧密且加强了相应的类管状Au团簇的稳定性.最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)之间的能隙值在0.041 eV至0.138 eV区间,表明Au_nSi₁₂具有较高的化学活性.电子结构分析显示,Si原子和Au原子之间的p-d轨道杂化在形成和维持Au_nSi₁₂的类管状结构方面发挥了重要作用.Hirshfeld电荷分析显示,电荷从Au原子转移到Si原子上,Au_n...     

聚噻吩中双电子极化子附近的二维局域振动模

将聚噻吩的一维SSH孤子模型推广到二维平面,研究了聚噻吩双电子极化子附近的二维局域振动模.计算结果表明双电子极化子附近存在15个局域振动模,其中4个奇宇称模与4条强红外吸收谱线1020,1120,1200,1323cm^-1相对应,4个偶宇称模恰与4条Raman吸收峰700,1047,1175,1220cm^-1一致. 关键词：     

Stability and Growth Modes of Ni--C Clusters: A Study based on All-Electron Density Function Theory

Growth modes of the free-standing NiCN （N ≤ 8） and Ni2CN （N ≤ 8） dusters are investigated by the allelectron density functional theory. The results reveal that there are two competing modes for the growth of these clusters： the linear chain and the ring structure without transannular bonds. The lowest-energy geometries of NiCN （N ≤ 8） are the linear chains with the Ni atom at one end, except for NiC2 and NiCT. The Ni2CN （N ≤ 8） clusters all prefer to the linear chains with the two Ni atoms at the two ends. Miilliken population analysis indicates that the total spin of the lowest-energy cluster show significant odd-even alternation. The NiMCN （M = 1,2） clusters with the even N are one and those with the odd-N are zero.     

Configurations, Electronic Structure and Magnetic Ordering of Small Manganese Clusters

We investigate the configurations, electronic structures, and magnetic ordering of MnN （N = 2-13） clusters based on all-electron density functional theory. The Jahn-Teller effect plays an important role in determining the ground state of certain geometries. The magnetic ordering of the MnN dusters transits from ferromagnetic ordering for the smallest （ N = 2, 3） dusters to a near degeneracy state including ferromagnetic and ferrimagnetic ordering in the vicinity of N = 4-6 and to a clear ferrimagnetic ordering at N = 7 or beyond. N = 6 and 10 are the magic numbers for neutrai MnN （N = 2-13） dusters.