Structural, electronic and vibrational properties of indium oxide clusters

Geometric, electronic and vibrational properties of the most stable and energetically favourable configurations of indium oxide clusters In_mO_n (1≤m, n≤4) are investigated using density functional theory. The lowest energy geometries prefer the planar arrangement of the constituent atoms with a trend to maximize the number of ionic In-O bonds. Due to the charge transfer from In to O atoms, the electrostatic repulsion occurs between the atoms with the same kind of charge. The minimization of electrostatic repulsion and the maximization of In-O bond number compete between each other and determine the location of the isometric total energy. The most stable linear In-O-In-O structure of In₂O₂ cluster is attributed to the reduced electrostatic repulsive energy at the expense of In-O bond number, while the lowest energy rhombus-like structure of In₂O₃ cluster reflects the maximized number of In-O bonds. Furthermore, the vibrational frequencies of the lowest energy clusters are calculated and compared with the available experimental results. The energy gap and the charge density distribution for clusters with varying oxygen/indium ratio are also discussed.     

Remote preparation of a two-particle state using a four-qubit cluster state

We present a scheme of remote preparation of two-particle states using a particular four-qubit cluster state as the quantum channel. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. Our results show that in general such remote state preparation can be realized with a probability of 1/4. But in several special cases, the probability of success can be improved to 1/2 or even 1.     

基于改进粒子群优化算法的氩原子团簇结构优化

采用改进粒子群优化算法(IPSO)结合Lennard-Jones势对氩原子团簇结构进行优化,得到了氩原子团簇的稳态结构能量。以氩原子团簇Arn（n = 2-14）为例,验证了该方法的有效性。结果表明,应用本文提出的方法可得到对称性良好的团簇结构。与基本粒子群优化算法(BPSO)及遗传算法(GA)相比,改进粒子群优化算法具有更好的收敛特性,能较快地得到氩原子团簇结构的最优解。     

Mn12-Ac磁性分子团簇单晶的热重-差热分析与结构转变

通过热重-差热分析(TG-DTA)，考察了Mn12-Ac磁性分子晶体从室温到270℃的热失重过程.结合x射线粉末衍射分析，认为在第一个失重阶段，即25—110℃，Mn12-Ac失去了处于团簇分子间隙的结晶乙酸和结晶水，同时失去了团簇分子中与4个Mn3+配位的4个H2O，Mn12-Ac单晶结构被破坏，但是团簇分子的基本结构依然存在；在第二个失重阶段，即180—230℃，Mn12-Ac转变为γ-Mn2O3，其中混有少量Mn3O4. 关键词： Mn12 分子团簇 热重-差热分析 x射线衍射     

载能团簇离子在物质中的能量损失

实验表明,团簇离子在物质中的能量损失并不等于各成分单独作用的总和,而是具有非线性效应．这种非线性效应与团簇离子的能量、团簇的种类和大小、团簇成分之间的空间关联程度以及作用物质的结构有关．对团簇作用的非线性效应研究对于了解团簇与物质相互作用的机制具有非常重要的理论意义．MeV能区的团簇离子在物质中的非线性电子能损和核能损方面的直接实验数据还相当缺乏,其理论模型也更待建立．评述了载能团簇离子在物质中的能量损失及测量方法．Fast ions deposit energy in matter through electronic and nuclear collision processes. The relaxation of the deposited energy induces emission of photons, electrons, ions, and neutral species from the target. Comparing with single incident ion, cluster induces many new phenomena: such as non-linear energy loss, non-linear emission of secondary ions, production of giant tracks and craters in various irradiated materials. These new phenomena induced by clusters are attributed to the vicinage effect ......     

双金属掺杂M2@Si20(M=Ti, Zr, Hf)团簇结构和性质的理论研究

采用密度泛函理论(DFT)和相对论有效原子核势近似(RECP),对M2@Si20(M=Ti,Zr,Hf)团簇的几何结构和电子结构性质进行研究,发现内嵌的金属二聚体和十二面体硅笼构成了稳定的富勒烯结构。通过对团簇电子结构的分析,结果表明Si20团簇掺杂双金属后稳定性得到了提高。对团簇的电荷布局分析表明过渡金属原子(Ti, Zr, Hf)和硅笼之间发生了电荷反转。     

利用Gupta势研究ConCu13-n (n=1～12)混合团簇的基态结构和熔化行为

利用Gupta多体相互作用势结合遗传算法和分子动力学方法模拟研究了ConCu13-n (n=0～13)单质及混合团簇的基态结构和熔化行为,结果表明：ConCu13-n (n=1~12)混合团簇的基态结构均是在单质Co13、Cu13基态二十面体基础之上的畸变,Co原子先占据中心后占据表面,表面上的Co原子总连接在一起,抱团分布;分析二级差分能和混合能发现Co1Cu12、Co7Cu6具有相对高的稳定性,可视为幻数结构团簇;ConCu13-n (n=1~12)混合团簇的熔点均位于Co13、Cu13单质团簇的熔点之间,且随着Co原子数目的增多总体呈上升趋势,但在n=3时出现反常（熔点降低）,这可归因于Co3Cu10的基态与第一激发态之间的能量差远小于Co2Cu11的相应值。     

Cluster synchronization in a network of non-identical dynamic systems

Cluster synchronization in a network of non-identical dynamic systems is studied in this paper, using two-cluster synchronization for detailed analysis and discussion. The results show that the common intercluster coupling condition is not always needed for the diffusively coupled network. Several sufficient conditions are obtained by using the Schur unitary triangularization theorem, which extends previous results. Some numerical examples are presented for illustration.     

A new quantum statistical evaluation method for time correlation functions

Considering a system ofN identical interacting particles, which obey Fermi-Dirac or Bose-Einstein statistics, we derive new formulas for correlation functions of the type (whereB _j is diagonal in the free-particle states) in the thermodynamic limit. Thereby we apply and extend a superoperator formalism, recently developed for the derivation of long-time tails in semiclassical systems. As an illustrative application, the Boltzmann equation value of the time-integrated correlation functionC(t) is derived in a straightforward manner. Due to exchange effects, the obtained t-matrix and the resulting scattering cross section, which occurs in the Boltzmann collision operator, are now functionals of the Fermi-Dirac or Bose-Einstein distribution.     

Three-body problem in the theory of the dielectric constant

We study the corrections to the Clausius-Mossotti formula for the dielectric constant of a disordered system of polarizable spherical particles. Previously we have derived an exact cluster expansion for the correction terms. Here we study the three-body correction in detail. We derive an explicit expression for the integrand of the three-body cluster integral for a system of polarizable point dipoles.