Analytical Evaluation of Multicenter Multielectron Integrals of Central and Noncentral Interaction Potentials over Slater Orbitals Using Overlap Integrals and Auxiliary Functions

Using expansion formulas for central and noncentral interaction potentials (CIPs and NCIPs, respectively) in terms of Slater type orbitals (STOs) obtained by the author (I.I. Guseinov, J. Mol. Model., in press), the multicenter multielectron integrals of arbitrary interaction potentials (AIPs) are expressed through the products of overlap integrals with the same screening parameters and new auxiliary functions. For auxiliary functions, the analytic and recurrence relations are derived. The relationships obtained for multicenter multielectron integrals of AIDs are valid for the arbitrary quantum numbers, screening parameters and location of orbitals.     

Calculation of Multicenter Nuclear Attraction and Electron Repulsion Integrals over Slater Orbitals by Fourier Transform Method Using Gegenbauer Polynomials

In this study, using complete orthonormal sets of exponential type orbitals (ETOs), a single closed analytical relation is derived for a large number of different expansions of overlap integrals over Slater type orbitals (STOs) with the same screening parameters in terms of Gegenbauer coefficients. The general formula obtained for the overlap integrals is utilized for the evaluation of multicenter nuclear attraction and electron repulsion integrals appearing in the Hartree–Fock–Roothaan equations for molecules. The formulas given in this study for the evaluation of these multicenter integrals show good rate of convergence and great numerical stability under wide range of quantum numbers, scaling parameters of STOs and internuclear distances.     

An Efficient Approach for the Calculation of Nuclear Overlap Integrals by Means of Binomial Coefficients and Its Application

This paper examines the computational efficiency of the method of evaluating nuclear overlap integrals commonly encountered in nuclear reactions. As will be seen, the present formulation yields compact closed-form expressions which will make the calculation of nuclear overlap integrals easy. For practical applications, the computational technique used must be amenable to rapid evaluation and yield an acceptable degree of accuracy. Finally, the ratios for the non-Borromean two-nucleon halo systems are calculated by using new formulas which are important for the reaction analyses. The results of this calculation have been compared with those obtained according to one of the theoretical articles (Timofeyuk et al., Phys. Rev. C 68:021601(R), 2003). The same numerical results are presented for significant examples and they are briefly discussed.     

Atomic structure and stability of elliptical carbon onion

Elliptical carbon onions were produced from amorphous carbon by electron beam irradiation. Atomic structure and structural stability of the onion were investigated by high-resolution electron microscopy, molecular mechanics calculation and molecular orbital calculation, and a structure model of C₂₄@ C₈₄ was proposed at the center of the elliptical onion. Received 30 November 2000     

Li-Ga-S体系热力学函数的第一性原理计算

采用第一性原理的平面波赝势法计算Li-Ga-S体系LiGa,Li₂S,GaS,Ga₂S₃和LiGaS₂的热力学数据,分析可能发生的化学反应,其中4个化学反应可以生成目标产物LiGaS₂.单质直接化合生成LiGaS₂的反应自由能变较高,Li₂S与Ga₂S₃化合生成LiGaS₂的反应自由能变随温度升高而降低,但体系很难获得Ga₂S₃,LiGa与S生成LiGaS₂和Li₂S与GaS化合生成LiGaS₂的自由能变较小,且体系生成Li₂S,GaS和LiGa的自由能变也较小,由此推断LiGaS₂多晶原料可以通过后两个反应获得.     

具有同空间特性的双波长可调谐TEACO2激光器

研制成功一种新型双波长TEACO2激光器,激光器在一对横向放电电极之间设置两个空间部分重叠的光栅_平面腔,两光栅沿腔轴一前一后放置,且在空间上交叠,两个腔相互利用,能够输出含有两种波长成分的激光脉冲。输出的同一激光脉冲中两波长激光场在空间上部分重叠,重叠程度和两种波长激光场的能量比均可通过调整前面光栅的水平横向位置加以控制,通过调节两光栅的角度选择所需支线,波长调谐方便且调谐范围较宽。该激光器在分离硼同位素的实验中得到了初步成功的应用。     

通过HSQC和1H,13C-COSY叠合增强二维谱分辨率的方法

通常二维谱F₁维分辨率较差,F₂维分辨率较好. 即HSQC实验¹³C维度分辨率较差,¹H维度分辨率较好. 而¹H, ¹³C-COSY实验¹³C维度分辨率较好,¹H维度分辨率较差. 提出一种通过HSQC和¹H, ¹³C-COSY叠合,取较弱的值储存并显示的方法增强分辨率,采用Bruker Topspin软件AU程序实现. 该方法在不明显增加采样时间的情况下,可显著增强分辨率,信噪比也没有降低. 同时抑制了F₁噪声. 处理后,谱图美观清晰.     

Independent particle model of spontaneous symmetry breaking in planar π-electron systems

The singlet stability of symmetry adapted (SA), restricted Hartree-Fock (RHF) solutions, and the implied symmetry breaking for several planar, π-electron systems, is investigated using the semiempirical Pariser-Parr-Pople Hamiltonian in the whole range of the coupling constant. We focus here on highly symmetric cyclic polyenes C₁₀H₁₀ and C₁₄H₁₄ and their various distorted analogues of lower symmetry, in particular on the perimeter models of naphthalene and anthracene (p-naphthalene and p-anthracene) modeling the so-called [n]-annulenes. Relying on earlier results for general systems with conjugated double-bonds, we explore the character and properties of both the SA and broken-symmetry (BS) RHF solutions for these systems and relate their behavior to those of highly symmetric cyclic polyenes and corresponding polyacenes. In this way we are able to provide a better understanding of the spontaneous symmetry breaking in these systems at the Hartree-Fock level of approximation.     

Approximate formulae for the overlap integral of two harmonic oscillator wave functions

The use of second-order perturbation theory to derive approximate formulae for the overlap integral of two harmonic oscillator wave functions is discussed, and the results applied to the theory of intensity distributions in vibrational progressions in electronic spectra. For the vibrational progression m←0 an approximate formula is given which, when the vibrational frequencies of the initial and final states differ by less than 10%, reproduces to an accuracy of 1% or less the intensity profile calculated using the exact formulae for the overlap integrals.     

Topology of dynamical lattice configurations including results from dynamical overlap fermions

We investigate how the topological charge density in lattice QCD simulations is affected by violations of chiral symmetry caused by the fermion action. To this end we compare lattice configurations generated with a number of different actions including first configurations generated with exact dynamical overlap quarks. We visualize the topological profiles after mild smearing. In the topological charge correlator we measure the size of the positive core, which is known to shrink to zero extension in the continuum limit. To leading order we find the core size to scale linearly with the lattice spacing with the same coefficient for all actions, even including quenched simulations. In the subleading term the different actions vary over a range of about 10%. Our findings suggest that non-chiral lattice actions at current lattice spacings do not differ much for observables related to topology, both among themselves and compared to overlap fermions.