Supercubooctahedron (Cs6Cl)2Cs5[Ga15Ge9Se48] Exhibiting Both Cation and Anion Exchange

A novel type of supertetrahedral connectivity is exhibited by the 72‐atom discrete supercubooctahedron in (Cs₆Cl)₂Cs₅[Ga₁₅Ge₉Se₄₈] ( 1 ), which undergoes both cation and anion exchange, as revealed by unambiguous single‐crystal X‐ray diffraction data. Electronic‐structure studies helped to understand the Ge/Ga distribution.     

Peptoid‐Ligated Pentadecanuclear Yttrium and Dysprosium Hydroxy Clusters

A new family of pentadecanuclear coordination cluster compounds (from now on simply referred to as clusters) [{Ln₁₅(OH)₂₀(PepCO₂)₁₀(DBM)₁₀Cl}Cl₄] (PepCO₂=2‐[{3‐(((tert‐butoxycarbonyl)amino)methyl)benzyl}amino]acetate, DBM=dibenzoylmethanide) with Ln=Y and Dy was obtained by using the cell‐penetrating peptoid (CPPo) monomer PepCO₂H and dibenzoylmethane (DBMH) as supporting ligands. The combination of an inorganic cluster core with an organic cell‐penetrating peptoid in the coordination sphere resulted in a core component {Ln₁₅(μ₃‐OH)₂₀Cl}²⁴⁺ (Ln=Y, Dy), which consists of five vertex‐sharing heterocubane {Ln₄(μ₃‐OH)₄}⁸⁺ units that assemble to give a pentagonal cyclic structure with one Cl atom located in the middle of the pentagon. The solid‐state structures of both clusters were established by single‐crystal X‐ray crystallography. MS (ESI) experiments suggest that the cluster core is robust and maintained in solution. Pulsed gradient spin echo (PGSE) NMR diffusion measurements were carried out on the diamagnetic yttrium compound and confirmed the stability of the cluster in its dicationic form [{Y₁₅(μ₃‐OH)₂₀(PepCO₂)₁₀(DBM)₁₀Cl}Cl₂]²⁺. The investigation of both static (dc) and dynamic (ac) magnetic properties in the dysprosium cluster revealed a slow relaxation of magnetization, indicative of single‐molecule magnet (SMM) behavior below 8 K. Furthermore, the χT product as a function of temperature for the dysprosium cluster gave evidence that this is a ferromagnetically coupled compound below 11 K.     

Observation of Slow Relaxation and Single‐Molecule Toroidal Behavior in a Family of Butterfly‐Shaped Ln4 Complexes

A family of five isostructural butterfly complexes with a tetranuclear [Ln₄] core of the general formula [Ln₄(LH)₂(μ₂‐η¹η¹Piv)(η²‐Piv)(μ₃‐OH)₂]?x H₂O?y MeOH?z CHCl₃ ( 1 : Ln=Dy^III, x=2, y=2, z=0; 2 : Ln=Tb^III, x=0, y=0, z=6; 3 : Ln=Er^III, x=2, y=2, z=0; 4 : Ln=Ho^III, x=2, y=2, z=0; 5 : Ln=Yb^III, x=2, y=2, z=0; LH₄=6‐{[bis(2‐hydroxyethyl)amino]methyl}‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)picolinohydrazide; PivH=pivalic acid) was isolated and characterized both structurally and magnetically. Complexes 1 – 5 were probed by direct and alternating current (dc and ac) magnetic susceptibility measurements and, except for 1 , they did not display single‐molecule magnetism (SMM) behavior. The ac magnetic susceptibility measurements show frequency‐dependent out‐of‐phase signals with one relaxation process for complex 1 and the estimated effective energy barrier for the relaxation process was found to be 49 K. We have carried out extensive ab initio (CASSCF+RASSI‐SO+SINGLE_ANISO+POLY_ANISO) calculations on all the five complexes to gain deeper insights into the nature of magnetic anisotropy and the presence and absence of slow relaxation in these complexes. Our calculations yield three different exchange coupling for these Ln₄ complexes and all the extracted J values are found to be weakly ferro/antiferromagentic in nature (J₁=+2.35, J₂=?0.58, and J₃=?0.29 cm^?1 for 1 ; J₁=+0.45, J₂=?0.68, and J₃=?0.29 cm^?1 for 2 ; J₁=+0.03, J₂=?0.98, and J₃=?0.19 cm^?1 for 3 ; J₁=+4.15, J₂=?0.23, and J₃=?0.54 cm^?1 for 4 and J₁=+0.15, J₂=?0.28, and J₃=?1.18 cm^?1 for 5 ). Our calculations reveal the presence of very large mixed toroidal moment in complex 1 and this is essentially due to the specific exchange topology present in this cluster. Our calculations also suggest presence of single‐molecule toroics (SMTs) in complex 2 . For complexes 3 – 5 on the other hand, the transverse anisotropy was computed to be large, leading to the absence of slow relaxation of magnetization. As the magnetic field produced by SMTs decays faster than the normal spin moments, the concept of SMTs can be exploited to build qubits in which less interference and dense packing are possible. Our systematic study on these series of Ln₄ complexes suggest how the ligand design can help to bring forth such SMT characteristics in lanthanide complexes.     

非正态变异下的非线性轮廓异常点识别方法研究

在质量控制领域,非线性轮廓异常点识别问题是重点研究问题之一。本文综合运用了小波分析、数据深度、聚类分析等数据分析处理技术,提出了一种新的非正态变异的异常点识别方法。文章通过仿真分析技术,将新方法χ²与控制图方法进行性能对比,结果证实新方法能够以更高的准确率和稳定性识别异常点,表现出更好的异常点识别性能。最后将新方法应用于木板垂直密度轮廓实例对新方法进行验证,分析结果表明本方法能够有效识别出异常轮廓数据。     

基于聚类和动态规划的组合路径策略

为提高电商仓库的拣货作业效率,本文提出了基于聚类和动态规划的组合路径策略,实现了生成路径消耗时间和路径长度之间的平衡,并将这一策略成功地应用到多区型仓库。该策略分四步:首先,根据待拣储位分布特征,运用聚类分析法对其进行分类;然后,以各类的首末储位作为节点,运用动态规划法对已得分类进行排序,得到相应的类序;其次,得到各类内部路径;最后,依次拣取待拣商品,并返回出发点完成拣货作业。在提出新的路径策略后,通过仿真方法将新策略与三种传统路径策略(穿越策略、最大间隙策略和混合策略)和一种优质算法(蚁群算法)进行了对比分析,结果表明:该策略具备良好的适用性和实用性。     

Behind the success of modified coupled-cluster methods: addition by subtraction

ABSTRACT

Modified coupled-cluster (CC) methods such as linearized coupled-cluster doubles (LinCCD), approximate coupled pair (ACP D14), 2CC (from nCC family), parameterized CCSD (pCCSD) and distinguishable cluster (DCSD) can have their advantages over general CC methods. Though these methods include connected clusters of single and double excitations at most, distinguishable cluster, parameterized CC and approximate coupled pair methods, in particular, have been shown to produce quantitatively correct results in benchmark studies. To put these methods on a stronger foothold, it is essential to understand the rationale for their success: mimicking the effect of connected triple excitations. We exploit the relation between CC and many body perturbation theory (MBPT) in general, and between CCSD and MBPT(4)/MP4 in particular, to take a step towards bringing clarity to this persisting conundrum. Our aim here is to look for numerical signs of ‘addition by subtraction’ or ‘inclusion by deletion’ effect that is likely behind the success of these modified CCD or CCSD methods. We achieve this by revisiting well-studied examples of single and multiple bond dissociation and comparing the performance of these modified CCSD methods with higher-level CC methods. Though our results are qualitative in nature, we hope this would lead to more rigorous analysis in future studies.     

多元统计分析方法的理论研究及应用分析

多元统计分析在多指标实际问题的研究中起着重要的作用.以往文献中,一般采用某一种多元统计方法对一个多指标实际问题进行研究,但其结果存在一定的偏差性.采用四种典型的多元统计方法:主成分分析法、因子分析法、分层聚类和K-均值聚类方法对同一个多指标银行问题进行研究,并对四种方法的不同结果进行比较综合分析,这样可以避免单一方法的偏差性,以便得到的结果更合理、更具有说服力.     

快凝Pd82Si18合金原子团簇的演化特性及遗传机制

采用分子动力学(MD)模拟计算,对Pd82Si18合金快凝过程中基本原子团簇的遗传特性、演化趋势和结构稳定性进行了研究.团簇类型指数法(CTIM)分析表明:非晶固体中Si原子为中心的(102/14418/1551)双帽阿基米德反棱柱(BSAP)团簇数目占据优势.快凝过程中,BSAP结构团簇具有最大的遗传分数,并且其他以Si原子为中心的Kasper团簇大多都会向BSAP结构团簇转变.通过对Si原子为中心的Kasper基本团簇电子性质第一性原理计算发现,体系中BSAP团簇的结合能最低,结构稳定性较高,与分子动力学计算结果一致.     

Structured water chains in external electric fields

ABSTRACT

We study the structural, energetic and electronic properties of the structured water chain clusters within the density functional theory. We refer the structured water chains to those water clusters that have specific geometric patterns stretched along one direction. External electric field required to keep the structures open chain, thereby preventing them to form closed structures, is applied along the length of the chain. The structures are essentially periodic with basic repeating unit consisting of the corner- or edge-sharing 4-, 5- or 6-membered ring water clusters. Our calculations underscore the possible existence of such structured water clusters in the electrostatic environments, which we simulate in its simplicity employing a dipolar, uniform and static electric field. Analysis reveals that the 5-membered ring water chain clusters, i.e. the pentamer chain clusters have the lowest average dipole moment per water molecule while the threshold field, that marks the onset of the field-induced closure of the HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap, is highest, followed by that for the tetramer and hexamer chains. The results suggest that the pentamer chains are the most stable clusters over a wide range of electric fields.