The(q\bar q) - pion and its decay constant in a chiral potential modeland its decay constant in a chiral potential model

Pion mass and its decay constant have been studied in a chiral symmetric potential model of independent quarks. The non-perturbative multi-gluon interaction which is responsible for quark confinement in a hadron is phenomenologically represented here by an effective potentialU(r) = 1/2(1 +γ ⁰)(ar ² +V ₀). The residual interactions due to quark-pion coupling arising out of the chiral symmetry preservation and that due to quark-gluon coupling arising out of single-gluon exchange are treated as low order perturbations. The centre of mass correction is also taken into account appropriately. This leads to the mass in consistency with that of the PCAC-pion and the pion decay constant in reasonable agreement with experiment.     

On the alleged equivalence of certain field theories

We critically examine some recent claims that certain field theories with and without boson kinetic energy terms are equivalent. We point out that the crucial element in these claims is the finiteness or otherwise of the boson wavefunction renormalisation constant. We show that when this constant is finite, the equivalence proof offered in the literature fails in a direct way. When the constant is divergent, the claimed equivalence is only a consequence of improper use of divergent quantities.     

PuNO分子结构与势能函数

本文运用密度泛函理论的B3LYP方法, 对钚原子应用LANL2DZ收缩价基函数, 氮、氧原子采用AUG-cc-pVTZ基函数, 分别对PuN, PuO, NO和PuNO体系进行了结构优化, 得到PuNO分子最稳构型为C_∞v (Pu-N-O), 电子态为⁶Σ^- (基态), 平衡核间距R_ON=0.12257 nm, R_NPu=0.22951 nm, 离解能D_e=8.10537 eV. 同时优化得到PuNO 分子存在两种亚稳态平衡构型分别为C_∞v (Pu-O-N), ⁶Σ^- (电子态)和C_s (O-Pu-N), A" (电子态), 以及分子体系相应的力学常数等. 拟合出PuN, PuO 和NO 分子的Murrell-Sorbie势能函数, 并使用多体项展式理论得到了PuNO分子的分析势能函数, 其等值势能图准确再现了PuNO分子最稳态构型及两个亚稳态构型的离解能和结构特性, 由此讨论了该分子体系的势能面静态特征.     

Renormalization and Quantum Scaling of Frenkel–Kontorova Models

We generalise the classical Transition by Breaking of Analyticity for the class of Frenkel–Kontorova models studied by Aubry and others to non-zero Planck’s constant and temperature. This analysis is based on the study of a renormalization operator for the case of irrational mean spacing using Feynman’s functional integral approach. We show how existing classical results extend to the quantum regime. In particular we extend MacKay’s renormalization approach for the classical statistical mechanics to deduce scaling of low frequency effects and quantum effects. Our approach extends the phenomenon of hierarchical melting studied by Vallet, Schilling and Aubry to the quantum regime     

Quark-antiquark scattering phase shift and meson spectral function in pion superfluid

We study the quark-antiquark scattering phase shift and meson spectral function in the pion superfluid described by the Nambu-Jona-Lasinio model. Meson mixing in the pion superfluid dramatically changes the full scattering phase shift and significantly broadens the spectral function of some collective modes.     

Modified scaling function projective synchronization of chaotic systems

This paper investigates a kind of modified scaling function projective synchronization of uncertain chaotic systems using an adaptive controller. The given scaling function in the new method can be an equilibrium point, a periodic orbit, or even a chaotic attractor in the phase space. Based on LaSalle's invariance set principle, the adaptive control law is derived to make the states of two chaotic systems function projective synchronized. Some numerical examples are also given to show the effectiveness of the proposed method.     

ZrH、CoH和ZrCoH分子的结构与势能函数

采用相对论有效原子实势(RECP)和密度泛函(B3LYP/SDD)方法,计算得到了ZrH、CoH和ZrCoH分子结构,分子的力学、光谱性质和势能函数.结果表明,ZrH的基态分别为X2∑,CoH和ZrCo的基态为X3Φ重态和X4∑重态,基态离解能分别为2.84 eV,2.50 eV和1.22 eV,谐振频率分别为1 686.59 cm-1,1 861.47 cm-1和168.62 cm-1,二阶力常数分别为167.0 aJ.nm-2,202.0 aJ.nm-2和60.0 aJ.nm-2.优化结果表明,HZrCo分子的基电子状态为X5A″,具有Cs对称性,基态离解能为5.055 eV,谐振频率分别为ν1(A′)=192.892 cm-1、ν2(A′)=322.624 cm-1和ν3(A′)=1 590.789 cm-1.应用多体项展式理论,计算确定了基态HZrCo的分析势能函数,该函数正确反映了HZrCo分子的结构特点,可用于研究HZrCo的微观反应动力学.     

高压下钒的结构相变研究

运用密度泛函理论研究了钒(Vanadium)在高压下的结构相变。 通过对体心立方(bcc)结构的钒在不同压强下剪切弹性系数C44的计算, 发现当压强约95 GPa时 C44＜0, 说明体心立方结构的钒在此条件下是不稳定的。 进一步计算分析得到钒在高压下发生了从体心立方到菱面体 (Rhombohedral)的结构相变, 相变压强约70 GPa, 这一结果与最近的实验结果符合。 还首次发现当压强约380 GPa时, 将会发生菱面体到体心立方的结构相变, 这有待实验的验证。We have studied the structure phase transition of Vanadium under high pressures by density function theory. A mechanical instability in the shear elastic constant (C44) has been found for body centred cubic(bcc) Vanadium at about 95 GPa, which indicates the existence of the structural transition. By calculation and analysis, we found that there was a bcc rhombohedral structure transition at the 70 GPa, which is consistent with the experiment data. Our calculations also firstly gave that there was a rhombohedral bcc structure transition at about 380 GPa, which needs to be verified by the experiment.     

分离作用射频四极场加速器的结构和工艺设计

 介绍了北京大学分离作用射频四极场(RFQ)加速器的结构特点,包括膜片式电极、支撑环式电极支撑系统、水冷系统、调谐系统及其工艺实现;介绍了基于该分离作用RFQ加速腔进行的调谐测试、高功率实验和束流实验。结果表明:调谐系统的频率调节范围及品质因数完全满足实验要求;分离作用RFQ加速腔的输入功率可以达到33 kW以上,满足高功率下稳定运行的条件;在束流实验中,把1.03 MeV的O⁺入射束流加速到1.65 MeV,半高宽能散小于3%。加速器结构满足物理设计要求,加速系统运行稳定。     

Steady-state scaling function of the (1 + 1)-dimensional single-step model

The steady-state height-height correlation function for the (1 + 1)-dimensional single-step model is calculated in a large-scale Monte Carlo simulation. Analysis of the data yields a universal ratio of scaling amplitudes which differs from the value obtained recently from a mode-coupling calculation. An empirical form for a universal scaling function is also presented.     

分离作用射频四极场加速器的结构和工艺设计

介绍了北京大学分离作用射频四极场(RFQ)加速器的结构特点,包括膜片式电极、支撑环式电极支撑系统、水冷系统、调谐系统及其工艺实现;介绍了基于该分离作用RFQ加速腔进行的调谐测试、高功率实验和束流实验。结果表明:调谐系统的频率调节范围及品质因数完全满足实验要求;分离作用RFQ加速腔的输入功率可以达到33 kW以上,满足高功率下稳定运行的条件;在束流实验中,把1.03 MeV的O+入射束流加速到1.65 MeV,半高宽能散小于3%。加速器结构满足物理设计要求,加速系统运行稳定。     

NCO异构体结构与分析势能函数

在B3LYP/6-31+G(d)水平上,对NCO分子的各种可能结构进行几何优化,得到了NCO及其异构体分子CNO和CON基态结构都是C∞v,电子态为X 2Π,NCO分子的平衡核间距RNC=0.1230nm, RCO=0.1186nm,离解能De=13.40eV,并计算出谐振频率ω1=1293.44cm-1, ω2(A΄)=484.73cm-1,ω2(A˝)=559.72cm-1,ω3=1988.41cm-1,Renner-Teller参数ε=-0.1429,计算值与实验值吻合较好．在此基础上,应用多体项展式理论,单体项中首次引入开关函数,三体项以NCO,CNO基态结构与性质为依据,拟合给出了NCO分子的基态分析势能函数,其等值势能图准确再现了NCO,CNO分子基态结构与特征,并与优化结果完全一致．     

NCO异构体结构与分析势能函数

在B3LYP/6-31+G（d）水平上,对NCO分子的各种可能结构进行几何优化,得到了NCO及其异构体分子CNO和CON基态结构都是C_∞v,电子态为X²Ⅱ,NCO分子的平衡核间距R_NC=0.1230 nm,R_CO=0.1186 nm,离解能D_e=13.40 eV,并计算出谐振频率ω₁=1293.44 cm^-1,ω₂（A′）=484.73 cm^-1,ω₂（A″）=559.72 cm^-1,ω₃=1988.41 cm^-1,Renner-Teller参数ε=-0.1429,计算值与实验值吻合较好.在此基础上,应用多体项展式理论,单体项中首次引入开关函数,三体项以NCO,CNO基态结构与性质为依据,拟合给出了NCO分子的基态分析势能函数,其等值势能图准确再现了NCO,CNO分子基态结构与特征,并与优化结果完全一致.     

Small-x behavior of the structure function and its slope for “frozen” and analytic strong-coupling constants

Using the leading-twist approximation of the Wilson operator product expansion with “frozen” and analytic versions of the strong-coupling constant, we show that the Bessel-inspired behavior of the structure function F₂ and its slope ∂lnF₂/∂ln(1/x) at small values of x, obtained for a flat initial condition in the DGLAP evolution equations, leads to good agreement with experimental data of deep-inelastic scattering at DESY HERA.     

Zeros of the finite-size scaling region partition function for a model with a wetting transition

We derive a finite-size scaling representation for the partition function for an Onsager-Temperley string model with a wetting transition, and analyze the zeros of this partition function in the complex scaled coupling parameter of relevance. The system models the one-dimensional interface between two phases in a rectangular two-dimensional region (x, y) ²,–L yL,oxN. The two phases are at coexistence. The string or interface has a surface tension 2KkT per unit length and an extra Boltzmann weighta per unit length if it touches the surfaces aty=±L. There is a critical valuea _c=1/2K and fora>a _c the string is confined to one of the surfaces, while fora a _c the string moves roughly in the rectangular region. The finite-size scaling parameters are =a _c ² N/L ² and =L(a–a _c)/a _c ² . We find that for || large, the zeros of the scaled partition function lie close to the lines arg()=±/4 with re()>0. We discuss the motion of all the zeros as changes by both analytic and numerical arguments.     

CH,NH和OH自由基基态与低激发态分子结构与势能函数

用电子相关耦合簇方法CCSD(T)和aug-cc-pVTZ基函数计算研究了CH, NH和OH自由基分子基态与低激发态的结构与势能函数，导出了分子的光谱数据.结果表明，CH, NH和OH自由基分子基态分别为X²Π，X³Σ和X²Π，基态与低激发态的势能函数均可用Murrell-Sorbie function来表达.CH自由基分子低激发态a⁴Σ^－和⁶Σ^－的绝热 关键词： 电子相关耦合方法 势能函数 结构 自由基     

大尺度相干结构的光学特性研究

根据大气近地面层对流湍池的实验结果,提出了一种用于描述大尺度相干结构的立体模型——椭球结构模型。计算并分析了该大尺度相干结构对光传输波前相位结构函数的影响,且和小尺度湍流结构作了比较。对于相同的参数,光线平行于间断面时造成的影响大于垂直于间断面;一般情况下,影响都很小;但当光线平行穿过具有三角波模型结构的间断面时可能产生较大的影响。