The Stability of Icosahedral Cluster and the Range of Interaction Potential

The relation between the stability of icosahedral clusters and the range of interaction potential is discussed. We found that the stability of icosahedral clusters may decrease with decreasing range of interaction potential. A simple formula about the critical number of icosahedral clusters and the range of interaction potential (M_c^1/3=A₁+A₂r_eff²) was proposed. The calculation of the stability of icosahedral fullerence molecular clusters shows that our idea is right.     

Formation Mechanism and Binding Energy for Body-Centred Regular Icosahedral Structure of Li13 Cluster

The formation mechanism for the body-centred regular icosahedral structure of Li13 cluster is proposed. The curve of the total energy versus the separation R between the nucleus at the centre and nuclei at the apexes for this structure of Li13 has been calculated by using the method of Gou＇s modified arrangement channel quantum mechanics （MACQM）. The result shows that the curve has a minimal energy of-96.951 39 a.u. at R = 5.46ao. When R approaches to infinity, the total energy of thirteen lithium atoms has the value of-96.564 38 a.u. So the binding energy of Lii3 with respect to thirteen lithium atoms is 0.387 01 a.u. Therefore the binding energy per atom for Lii3 is 0.029 77 a.u. or 0.810 eV, which is greater than the binding energy per atom of 0.453 eV for Li2, 0.494 eV for Li3, 0.7878 eV for Li4. 0.632 eV for Lis, and 0.674 eV for Liv calculated by us previously. This means that the Li13 cluster may be formed stably in a body-centred regular icosahedral structure with a greater binding energy.     

Formation Mechanism and Binding Energy for Icosahedral Central Structure of He13^＋ Cluster

The formation mechanism for the icosahedral central structure of the He13^ cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between two nuclei at the center and an apex of the icosahedral central structure. The result of the calculation has shown that the curve has a minimal energy -37.5765 (a.u.) at R=2.70ao. The binding energy of He13^ with respect to He^ 12He was calculated to be 1.4046 a.u. This means that the cluster of He13^ may be formed in an icosahedral central structure with strong binding energy.     

Formation Mechanism and Binding Energy for Icosahedral Central Structure of He1+3 Cluster

The formation mechanism for the icosahedral central structure of the He1 13 cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between two nuclei at the center and an apex of the icosahedral central structure. The result of the calculation has shown that the curve has a minimal energy -37.5765 (a.u.) at R = 2.70ao. The binding energy of He 13 with respect to He 12He was calculated to be 1.4046 a.u. This means that the cluster of He 13 may be formed in an icosahedral central structure with strong binding energy.     

二十面体Sc13，Sc13¬+1，Sc13¬-1团簇的稳定性与电子结构研究

采用密度泛函理论框架下的广义梯度近似(DFT/GGA),对Sc13团簇进行了几何结构优化,得到13原子钪团簇的基态结构为正二十面体(Ih),在此基础上对二十面体(Ih)Sc13, Sc13¬+1和Sc13-1团簇的稳定性、电子结构磁矩进行研究.结果发现Sc13,Sc13¬+1和Sc13¬-1团簇都在Ih结构时最稳定,该尺寸团簇的稳定性主要由二十面体密堆积构型决定;带电能使团簇的结构稍稍收缩从而使团簇的稳定性有所增强;团簇的键长和对称性对团簇的磁矩有很明显的影响.     

A Scheme for Generating Cluster States via Raman Interaction

A scheme for generating cluster states via Raman interaction is proposed. In the scheme, we firstly prepare cluster states of multi-cavities with information encoded in the coherent states and then generate cluster states of multiatoms, which encode the information in the ground states of A-type atoms. The advantages of our scheme are that the atomic spontaneous radiation can be efficiently reduced since the cavity frequency is largely detuned from the atomic transition frequency and the Hadamard gate operation of the coherent states is replaced by measuring the coherent states.     

Three-dimensional simulation on explosions of hydrogen atomic clusters irradiated by an intense femtosecond laser pulse

Using classic particle dynamics simulations, the interaction process between an intense femtosecond laser pulse and icosahedral hydrogen atomic clusters H_{13}, H_{55} and H_{147} has been studied. It is revealed that with increasing number of atoms in the cluster, the kinetic energy of ions generated in the Coulomb explosion of the ionized hydrogen clusters increases. The expansion process of the clusters after laser irradiation has also been examined, showing that the expansion scale decreases with increasing cluster size.     

The Quarkonium Potential Within the Short and Intermediate Range in QCD

A quark-antiquark potential is calculated by involving vacuum condensates up to dimension-6 in QCD in the background fields. The underlying assumption is that a gluon (quark) propagates, not in the empty space, but through the physics vacuum, filled with the background fields. The interactions of the gluon with the background fidds manifest themselves as the corrections of vacuum condensates to the free gluon propagator. It is shown that these corrections extend the potential from the short distances to the intermediate range. Indeed, with some reasonable parameters, the resulting potential is similar to those popular phenomenological potentials in shape in the region of 0.1 < γ < 1 fm.     

The Effects of Isoscalar MEC and Six-Quark Cluster on W1/W2 of the Deuteron

The ratio of the deuteron structure function W₁/W₂ in deuteron electrodisintegration in the threshold region has been calculated by using the hybrid quark-hadron model, including isoscalar MEC. Our investigation shows that isoscalar MEC and six-quark cluster have large effects on W₁/W₂.     

The Effect of Nanoscale Roughness on Long Range Interaction Forces

A model was developed to calculate the long range van der Waals and electrostatic energies between a rough colloidal particle and a smooth solid plate in aqueous solutions. The particle roughness was modeled as hemispherical asperities distributed uniformly over the surface. Because of the assumption of additive potentials used in calculating the electrostatic force, the model is most accurate when the particle/plate separation is larger than several Debye screening lengths, such as near the location of the secondary minimum. The model predicts that such roughness reduces the depth of the secondary minimum and pushes it to larger separation distances. The model also predicts that the height of the primary energy barrier, which controls the dispersion stability, is substantially lowered by the asperities.Experimental validation of the model was achieved by measuring the potential energy profile between individual, 15µm diameter polystyrene latex spheres and a smooth glass plate around the location of the secondary energy minimum using the optical technique of total internal reflection microscopy (TIRM). When compared to predictions made assuming perfectly smooth surfaces, the measured well depths are consistently found to be lower than expected. Excellent agreement can be achieved, however, by adding asperities with a height of order 25nm to the particle surface. These measurements are some of the first direct measurements of the effect of roughness on interaction energies.     

The Effect of Interaction Range in Relativistic Microscopic Optical Potentials

Starting from the Walecka model about relativistic nucleon-meson field theory,the effect of interaction range in the relativistic microscopic optical potentials for nucleon-nucleus is included by folding the optical potentials in Local Density Approximity with nucleon-nucleon interaction potentials from the Walecka model.The present potentials are used to analyze the proton elastic scattering from nuclei.The agreement of the present calculation with experiment data is better than that of LDA.     

The Formation Mechanism and Binding Energy for the Octahedral Central Structure of the He7+ Cluster

The formation mechanism for the octahedral central structure of the He7 cluster is proposed and its totalenergy curve is calculated by the method of a modified arrangement channel quantum mechanics (MACQM). The energyis a function of separation R between two nuclei at the center and an apex of the octahedral central structure. The resultof the calculation shows that the curve has a minimal energy -19.7296 a.u. At R = 2.40 α0. The binding energy of He7 with respect to He 6He was calculated to be 0.6437 a.u. This means that the cluster of He7 may be formed in thestable octahedral central structure with R = 2.40 α0.     

多重碎裂和相互作用势的涨落

中能重离子碰撞中相互作用势的等位线随时间的变化直观地给出了关于势能涨落的信息.碰撞初期在势能中心可能出现正值,随后在此区域的等位线形状不规则变形,特别是等位线负曲率的出现,导致核子的混沌运动.相邻核子的位相差随时间指数上升,造成相空间的分离,产生碎裂.     

The MACQM Calculation for the BInding Energy of the Equilateral Triangle Structure of H3^— Cluster

Considering that the equilateral triangle structure of H3^- cluster can be formed from the interaction of H^- with two hydrogen atoms,a modified arrangement channel quantum mechanics method has been used to calculate the total energy curve for this structure,The result shows that the cureve has a minimal energy-1.6672 a.u.at an internuclear distance of 1.77a0,so its dissociation energy(binding energy)is D(H^- H H)=0.1395,a.u.This means that the cluster H3^- may be formed in an equilateral triangle structure with a bond length of 1.77α0.     

A New Statistical Aspect of the Cluster Variation Method for Lattice Systems

This paper presents an alternative statistical way to derive the cluster variation method (CVM) for lattice systems. The formulation is developed for a series of different clusters, each of which is the largest overlap cluster between two clusters of the next larger type. We arrive at the CVM expression of the lattice configuration factor by deriving the number of different ways of distributing clusters of a selected type in the lattice so that they overlap each other at the largest overlap clusters in a physically correct manner. The essential assumption employed is that individual overlapping events are statistically independent of each other. This reveals a new statistical aspect of the CVM: The CVM is based on a Bethe tree of clusters of the selected type.     

HIRFL-CSR团簇靶的优化

为HIRFL-CSR团簇内靶设计加工了新的供气系统, 拆换了原有的喷嘴, 对氢气和氩气进行了新的实验, 获得了氢气和氩气的稳定团簇束, 解决了困扰团簇靶稳定运行的喷嘴堵塞问题. 获得的氢团簇束密度为1.75×10¹³ atoms/cm³, 好于德国GSI内靶对氢束所达到的1×10¹³atoms/cm³. 研究了团簇束的衰减, 测量了氢束和氩束的有效靶厚, 研究了团簇靶系统对这两种工作气体的长期运行稳定性. 对氢和氩两种工作气体, 各级气压呈现了良好的稳定性, 说明在实验的时间范围内, 团簇靶运行稳定.     

Ground-State Bands of Fm and No Isotopes in Cluster Model

We investigate the ground-state rotational bands of nuclei with Z ≥ 100 using cluster model proposed by Buck et al. [Phys. Rev. Lett. 94 (2005) 202501]. The core-cluster decomposition of each nucleus is determined by the corresponding electric quadrupole transition strength B(E2 : 2 → 0 ). The theoretical spectra of fermium and nobelium isotopes are compared with available experimental data. Good agreement between model and data is obtained.     

The Formation Mechanism and Binding Energy for the Octahedral Central Structure of the He7^＋ Cluster

The formation mechanism for the octahedral central structure of the He7^ cluster is proposed and its total energy curve is calculated by the method of a modified arrangement channel quantum mechanics (MACQM). The energy is a function of separation R between two nuclei at the center and an apex of the octahedral central structure. The result of the calculation shows that the curve has a minimM energy -19.7296 a.u. at R = 2.40α0. The binding energy of He7^ with respect to He^ 6He was calculated to be 0.6437 a.u. This means that the duster of He7^ may be formed in the stable octahedral central structure with R=2.40 α0.     

Ground-State Bands of Fm and No Isotopes in Cluster Model

We investigate the ground-state rotational bands of nuclei with Z 〉 100 using cluster model proposed by Buck et al. [Phys. Rev. Left. 94 （2005） 202501]. The core-duster decomposition of each nucleus is determined by the corresponding electric quadrupole transition strength B（E2 ： 2^＋ → 0^＋）. The theoretical spectra of fermium and nobelium isotopes are compared with available experimental data. Good agreement between model and data is obtained.