热核表面能的Thomas－Fermi统计模型理论

用Ｓｅｙｌｅｒ－Ｂｌａｎｃｈａｒｄ动量相关非定域相互作用的含温Ｔｈｏｍａｓ－Ｆｅｒｍｉ统计理论，对半无穷大核物质模型计算了核物质表面能系数σ（Ｔ，δ）随温度Ｔ和不对称度δ的变化，发现在低温Ｔ≤５ＭｅＶ和不对称度δ≤０．２时，可以近似写成σ（Ｔ，δ）＝σ０（Ｔ）［１＋Ｋ（Ｔ）δ２］，其中σ０（Ｔ）和Ｋ（Ｔ）可以拟合成温度Ｔ的二次函数．     

Ionization of Atoms and the Thomas-Fermi Model for the Electric Field in Crystal Planar Channels

The electric field in the crystal planar channels is studied by the Thomas Fermi method. The Thomas-Fermi equation and the corresponding boundary conditions are derived for the crystal planar channels. The numericalsolution for the electric field in the channels between (110) planes of the single crystal silicon and the critical angles ofchannelling protons in them are shown. Reasonable agreements with the experimental data are obtained. The resultsshow that the Thomas-Fermi method for the crystal works well in this study, and a microscopic research of the channelelectric field with the contribution of all atoms and the atomic ionization being taken into account is practical.     

锗团簇Ge65, Ge70, Ge75的稳定结构及其电子结构性质

将两种全局结构搜索方法(压缩液态法、遗传算法)与锗的紧束缚势模 型相互结合, 对Ge₆₅, Ge₇₀, Ge₇₅的稳定结构进行了大规模的搜寻,提 出能量较低的可能结构, 然后进一步利用第一性原理方法对这些低能结构进行精确 的优化计算, 确定出了这三种尺寸团簇的基态结构. 发现这三种团簇各具有两种稳定的并且能量相近的异构体: 类球形和类椭球形, 这与实验上报道的大尺寸团簇Ge_n (65 ≤ n ≤ 80) 的结构特征相符合. 简要地分析了这三种团簇基态结构的电子性质. 关键词： 锗团簇 紧束缚势 遗传算法 压缩液态法     

GeHn±(n=0,1,2)的势能函数和光谱常数研究

用密度泛函B3lyp/6-311++g(d,p)方法对 分子离子进行理论研究。结果表明：GeH,GeH+,GeH-1均能稳定存在,GeH+2和GeH-2有亚稳定态存在,其基态电子态分别是: 2Π(GeH),1Σ(GeH+),3Σ(GeH-),2Σ(GeH+2)和2Π(GeH-2),GeH+2和GeH-2的势能函数呈明显的‘火山态’型,导出了相应的分子离子的解析势能函数、光谱数据和力常数,比较了四参数、八参数Murrell-Sorbie势和Zhu-Wang势对不稳定分子势能函数的拟合情况,指出了用八参数Murrell-Sorbie势对‘火山态’型势能函数的拟合也是合适的;同时讨论了电荷对势能函数和能级的影响。     

球状物体作微形变时弹性势能的研究

研究一个弹性球在保持体积不变的前提下,形变为长旋转椭球时的弹性势能.首先通过最小势能原理和物理条件确定位移函数,然后根据弹性势能密度-应变-位移三者之间的关系,通过积分计算得到弹性势能,并且进行了有益的讨论.     

Methodological approaches for the free energy calculations in electroactive SAMs

We compare the Free Energy Perturbation (FEP) and Thermodynamic Integration (TI) approaches in slab-geometries where the electrostatic interactions are handled with the standard three-dimensionally Ewald summation technique. The comparison between FEP and TI is made through energy distributions in the analysis of the phase space sampling between the forward and backward directions, the reversibility of the perturbation, the number of windows and the consistency of the free energy decomposition into individual components. We report here free energy calculations in order to predict the shift in the redox potential in self-assembled monolayers (SAMs) as the coadsorbed chain length is changed. The reproduction of the free energies with respect to the electrolyte is tested on neutral and charged simulation cells.     

Solution of the Cauchy problem for a continuous limit of the Toda lattice and its superextension

A supersymmetric equation associated with a continuum limit of the classical superalgebra sl(n/n+1) is constructed. This equation can be considered as a superextension of a continuous limit of t the Toda lattice with fixed end-points or, in other words, as a supersymmetric version of the heavenly equation. A solution of the Cauchy problem for the continuous limit of the Toda lattice and for its superextension is given using some formal reasonings.     

利用Gupta势结合遗传算法研究ConCu55－n(n=0—55)混合团簇的结构演化及基态能量

采用半经验的Gupta多体势结合遗传算法对Co_nCu_55－n(n=0—55)混合团簇的基态结构和能量进行了研究,发现这些混合团簇的基态结构是在Co₅₅,Cu₅₅单质团簇(Mackay二十面体)的基础之上发生的畸变;从n=0(Cu₅₅)开始,Co原子从中心到表面,从棱到顶点依次、连续替换Cu原子;基态结构与键能较大键的数目及其平均键长有关;Co₁₃Cu₄₂具有最稳定的结构,13个Co原子全部位于团簇内部形成Mackay二十面体对整个团簇的稳定性有显著影响. 关键词： 团簇 结构和能量 Gupta势 遗传算法     

Solution of the Energy Level of Hydrogen-Like Atom for the Debye Shielding Potential

The first-order revision and the approximation analytical formula of the energy levels for hydrogen-likeatoms under the condition of Debye shielding potential are achieved by means of the Rayleigh-Schrodinger perturbationtheory; meanwhile, the corresponding recurrence relations are obtained from the use of the solution of power series. Basedon the above solutions and with the use of energy consistent method the equivalent value of second-order reversion underthe condition of Debye shielding potential is produced as well and the result is compared with the data obtained by thenumerical method. Besides, the critical bond-state and corresponding cut-off conditions are discussed.     

Analysis of atmospheric effects on the continuous variable quantum key distribution

Atmospheric effects have significant influence on the performance of a free-space optical continuous variable quantum key distribution (CVQKD) system. In this paper, we investigate how the transmittance, excess noise and interruption probability caused by atmospheric effects affect the secret-key rate (SKR) of the CVQKD. Three signal wavelengths, two weather conditions, two detection schemes, and two types of attacks are considered in our investigation. An expression aims at calculating the interruption probability is proposed based on the Kolmogorov spectrum model. The results show that a signal using long working wavelength can propagate much further than that of using short wavelength. Moreover, as the wavelength increases, the influence of interruption probability on the SKR becomes more significant, especially within a certain transmission distance. Therefore, interruption probability must be considered for CVQKD by using long-signal wavelengths. Furthermore, different detection schemes used by the receiver will result in different transmission distances when subjected to individual attacks and collective attacks, respectively.     

氧化物正电荷影响下半导体空间电势的近似解析解研究

建立了半导体空间电势与界面氧化物正电荷之间联系的解析表达式。从一维情况下精确的泊松方程及其边界条件出发,对N（P）型硅半导体中的泊松方程作积累（耗尽）近似,根据德拜屏蔽效应对边界条件作截断近似,得到了氧化物正电荷影响下两种类型半导体内电势的近似解析解。另外,还进行了精确数值计算,并将它与近似解析解的结果进行比较,结果表明,当氧化物正电荷增加到使P型半导体发生强反型后,近似解不再成立。根据强反型的条件,给出了P型半导体中近似解的适用范围。     

Effects of dispersion forces in the instability of polymer films

Spontaneous rupture of some polymer films upon heating is commonplace. The very criterion for this instability is the system free energy possessing a negative curvature. Within the framework of full frequency-dependent theory of dispersion forces, we have derived the excess free energy of a typical system---polystyrene film deposited on the silicon substrate. The excess free energy, wavelengths and growth rates are calculate and a comparison is made between the accurate results and the approximate results. It is found that the stability of the film can be tuned by the variation of the thickness of the coating and the retardation effects can be significant sometimes.     

理论计算中电势能零点的选取对电荷注入的影响

基于紧束缚的Su-Schrieffer-Heeger(SSH)模型,利用非绝热的动力学方法,研究了金属/聚合物结构中电势能零点的选取对电荷注入的影响.理论计算发现,电场越强,电势能零点的选取对电荷注入的影响就越大. 关键词： 电势能 电荷注入 非绝热动力学     

Theoretical study of the structures of MgO(1 0 0)-supported Au clusters

A theoretical method, which combines the first-principle calculations and a canonical Monte Carlo (CMC) simulation, was used to study the structures of Au clusters with sizes of 25-54 atoms supported on the MgO(1 0 0) surface. Based on a potential energy surface (PES) fitted to the first-principle calculations, an effective approach was derived to model the Au-MgO(1 0 0) interaction. The second moment approximation to the tight-binding potential (TB-SMA) was used to model the Au-Au interactions in the CMC simulation. It is found that the Au clusters with sizes of 25-54 atoms supported on the MgO(1 0 0) surface possess an ordered layered fcc epitaxial structure.     

Baxter's Solution for the Free Energy of the Chiral Potts Model

In honor of Baxter's sixtieth birthday, we would like to review some of his work on the free energy of the chiral Potts model. In spite of the enormous complexity and difficulty of the problem, Baxter, using functional relations was able to calculate not only the free energy, but also the interfacial tension. We here show that the integral for the free energy simplifies in the superintegrable case and is identical to his earlier results using entirely different approaches. His calculations are extended to include other regions. We also attempt to clarify some of his reasoning as several steps may be mysterious at first glance.     

Ionic Debye Screening in Dense Liquid Plasmas Observed for Li+p,d Reactions with Liquid Li Target

Thick target yields of a particles emitted in the ~6Li(d,a)~4 He and ~7Li(p,a)~4 He reactions were measured for Li target in the solid and liquid phase.Observed reaction rates for the liquid Li are always larger than those for the solid.This suggests that the stopping power of hydrogen ion in the liquid Li metal might be smaller than in the solid.Using the empirically obtained stopping power for the liquid Li,we have deduced the screening potentials of the Li+p and Li+d reactions in both phases.The deduced screening potential for the liquid Li is about 500 eV larger than for the solid.This difference is attributed to the effect of liquefied Li~+ ions.It is concluded that the ionic screening is much stronger than the electronic screening in a low-temperature dense plasmas.     

A new Monte Carlo power method for the eigenvalue problem of transfer matrices

We propose a new Monte Carlo method for calculating eigenvalues of transfer matrices leading to free energies and to correlation lengths of classical and quantum many-body systems. Generally, this method can be applied to the calculation of the maximum eigenvalue of a nonnegative matrix  such that all the matrix elements of Â^k are strictly positive for an integerk. This method is based on a new representation of the maximum eigenvalue of the matrix  as the thermal average of a certain observable of a many-body system. Therefore one can easily calculate the maximum eigenvalue of a transfer matrix leading to the free energy in the standard Monte Carlo simulations, such as the Metropolis algorithm. As test cases, we calculate the free energies of the square-lattice Ising model and of the spin-1/2XY Heisenberg chain. We also prove two useful theorems on the ergodicity in quantum Monte Carlo algorithms, or more generally, on the ergodicity of Monte Carlo algorithms using our new representation of the maximum eigenvalue of the matrixÂ.     

Mechanisms of interaction between luteolin and the catalytic zinc ion in matrix metalloproteinases: a computational study

Many experimental studies have found that flavonoids including luteolin can inhibit the activities of matrix metalloproteinases (MMPs), but the related theoretical studies are rather lacking. In this paper, we perform PM6 quantum chemistry calculations together with modeling of ligand‐water exchange reactions to investigate the mechanisms of interaction between luteolin and catalytic zinc ion in MMPs. The calculations show that the electron transfer from the luteolin molecule to the catalytic zinc ion in MMPs occurs when the catalytic zinc ion coordinates with the O atoms of substituent groups at various positions of A, B, and C rings of luteolin molecule. It is found that the more the number of the electron transfer from one coordinating O atom of substituent groups of luteolin molecule to the catalytic zinc ion, the stronger the coordinating ability between them. We further find that comparing with the O atoms of hydroxy groups at 5‐, 7‐, 3′‐, and 4′‐positions of luteolin molecule, the coordinating ability for the O atom of carbonyl group at its 4‐position with the catalytic zinc ion is the strongest, which indicates that when luteolin inhibits MMPs activity, the catalytic zinc ion should coordinate with the carbonyl group at 4‐position of luteolin molecule, rather than the hydroxy groups at its other positions, in agreement with the relevant experimental results reported in previous literature. This paper may be helpful for designing the new MMPs inhibitors having higher biological activities by carrying out the structural modifications of luteolin molecule. Copyright © 2012 John Wiley & Sons, Ltd.     

Full correction of spherical aberration for the lens with a spherical refractive index distribution

The potential to create a lens with a spherical gradient of refractive index, transforming a divergent entrance homocentric beam into a convergent output homocentric beam, is shown. The lens has the first and the second spherical surfaces. The second surface is isoindicial. The distribution law of the refraction index for the lens material, and the basic parameters of the lens are obtained in analytical form.     

Theoretical study on the complexes of He, Ne and Ar

This paper investigates the effect of basis sets through the potential energy curves(PECs) of six rare gas complexes He 2,Ne 2,Ar 2,He-Ne,He-Ar,and Ne-Ar.The coupled cluster singles and doubles method with perturbative treatment of triple excitations,doubly augmented basis sets of d-aug-cc-pVQZ,bond functions,and basis set superposition errors are employed.The diffuse function is more effective than the polarization function on describing the dissociation energy.The PECs are fitted into analytical potential energy functions(APEFs) using three expressions.It is found that all the expressions are suitable for describing the complexes of rare gases.Based on these APEFs,the spectroscopic parameters are calculated and the results are compared with the theoretical and experimental data available in the literature.