精确的甲烷分子价轨道的电子动量谱学研究

电子动量谱学（EMS）已发展成为探测原子分子电子结构的强有力工具．借助电子动量谱学可获得精确的分子轨道电子密度分布,并能提供非常详细的电子运动和电子关联信息．分子电子密度分布和电子运动的详细了解对分子的识别和化学活性的理解非常重要,并且也有助于计算机辅助的分     

f3组态离子在四角场中的基矢矩阵元

通过选用与群链[(O⊃D₄⊃C₄)×SU(2)]相匹配的单电子基矢,使其直积构成多电子fN体系的O⊃D₄⊃C₄旋量群的不可约表示的基矢,并讨论了有关的Coulomb矩阵元、Casimir矩阵元、旋-轨偶合矩阵元和晶体场作用矩阵元.     

Harmonic analysis and discrete polynomials. From semiclassical angular momentum theory to the hyperquantization algorithm

Orthogonal polynomials of a discrete variable have been widely investigated as fundamental tools of numerical analysis. This work aims to propose the extension of their use to quantum mechanical problems. By exploiting both their connection with coupling and recoupling coefficients of angular momentum theory and their asymptotic relationships (semiclassical limit) with spherical and hyperspherical harmonics, a discretization procedure, the hyperquantization algorithm, has been developed and applied to the study of anisotropic interactions and of reactive scattering. One of the most appealing features of this method turns out to be a drastic reduction of memory requirements and computing time for extensive dynamical calculations. Examples of the application of this technique to stereodirected dynamics via an exact representation for the S matrix as well as to the characterization of molecular beam polarization are also illustrated. Received: 17 September 1999 / Accepted: 3 February 2000 / Published online: 5 June 2000     

分子角动量定向布居的制备探测和它的碰撞弛豫

利用受激Raman泵浦,使线性分子C2H2选择性地制备振动态角动量定向布居参数A0(1)达到0.7～0.8。并测定了角动量定向布居碰撞诱导的弛豫速率常数。采用园偏振的紫外激光诱导荧光方法,可表征分子角动量定向布居的制备和它的碰撞弛豫过程。     

Frequency modulated spectroscopy as a probe of molecular collision dynamics

We describe the application of frequency modulated spectroscopy (FMS) with an external cavity tuneable diode laser to the study of the scalar and vector properties of inelastic collisions. CN X(2)Sigma(+) radicals are produced by polarized photodissociation of ICN at 266 nm, with a sharp velocity and rotational angular momentum distribution. The collisional evolution of the distribution is observed via sub-Doppler FMS on the A(2)Pi-X(2)Sigma(+) (2,0) band. He, Ar, N(2), O(2) and CO(2) were studied as collider gases. Doppler profiles were acquired in different experimental geometries of photolysis and probe laser propagation and polarization, and on different spectroscopic branches. These were combined to give composite Doppler profiles from which the speed distributions and specific speed-dependent vector correlations could be determined. The angular scattering dynamics with species other than He are found to be very similar, dominated by backward scattering which accompanies transfer of energy between rotation and translation. The kinematics of collisions with He are not conducive to the determination of differential scattering and angular momentum polarization correlations. Angular momentum correlations show interesting differences between reactive and non-reactive colliders. We propose that this reflects differences in the potential energy surfaces, in particular, the nature and depth of attractive potential wells.     

过渡金属络合物荷移光谱的研究

在配位场近似下,用不可约张量方法对具有O_4对称性的FeCl_6~(3-)及与其结构相似的过渡金属络合物的Hamilton矩阵进行了矩阵分割,得到了一种计算荷移光谱的简单方法.在计算中采用方案,考虑了纯组态内部的Coulomb作用和旋轨作用,忽略了不同组态间的Coulomb作用.并采取冻结轨道近似.计算结果与实验光谱数据符合较好.     

Stark mixing by ion-Rydberg atom (molecule) collisions

Classical molecular dynamics simulations are performed to cover Stark mixing transitions (nℓ→nℓ^′) in Rydberg atoms by collision with slow ions. Accuracy is tested by comparison with the exact analytical classical probabilities previously obtained when the ion–atom potential is taken as the long-range ion–dipole interaction. The results are provided not only for the ion–dipole interaction but also for the full electrostatic interaction. It is shown, by comparison, that the ion–dipole potential alone provides reliable probabilities. The method is highly accurate and is very amenable to ready inclusion of other processes competing with Stark mixing.     

单次碰撞条件下NH2(A2A1,(0,9,0))转动非弹性碰撞

在单次碰撞条件下 ,对NH2 (～A2 A1,(0 ,9,0 ) )的转动非弹性碰撞进行了详细的研究 ,包括不同转动能级、核自旋、及自旋分裂双重态的传能 ,直接得到了一些倾向性规则 ,并且对于能隙规律和角动量传递规律在其中的重要性作了初步探讨     

A new method for the stereoselective construction of angular methyl group of fuzed cyclic ethers

A convenient method for the stereoselective construction of angular methyl group of fuzed cyclic ethers is described. Reactions of mixed thioacetals with Me₂Zn/Zn(OTf)₂ afforded the corresponding methylated products in good yields. Various protective groups such as MOM ether, benzylidene acetal, TBS ether, and pivaloyl group were stable under the reaction conditions.     

对称群标准表示矩阵计算新方法

在多体问题的对称群方法中,群表示矩阵的计算是关键性问题。Young-Yamanouchi规则给出了标准正交表示的计算方法,然而该法相当繁琐,颇难使用,本文将2列Young表标准表示的计算方法[1]推广到任意不可约表示,给出对称群标准表示矩阵计算新方法.     

Efficient Implementation of High Dimensional Model Representations

Physical models of various phenomena are often represented by a mathematical model where the output(s) of interest have a multivariate dependence on the inputs. Frequently, the underlying laws governing this dependence are not known and one has to interpolate the mathematical model from a finite number of output samples. Multivariate approximation is normally viewed as suffering from the curse of dimensionality as the number of sample points needed to learn the function to a sufficient accuracy increases exponentially with the dimensionality of the function. However, the outputs of most physical systems are mathematically well behaved and the scarcity of the data is usually compensated for by additional assumptions on the function (i.e., imposition of smoothness conditions or confinement to a specific function space). High dimensional model representations (HDMR) are a particular family of representations where each term in the representation reflects the individual or cooperative contributions of the inputs upon the output. The main assumption of this paper is that for most well defined physical systems the output can be approximated by the sum of these hierarchical functions whose dimensionality is much smaller than the dimensionality of the output. This ansatz can dramatically reduce the sampling effort in representing the multivariate function. HDMR has a variety of applications where an efficient representation of multivariate functions arise with scarce data. The formulation of HDMR in this paper assumes that the data is randomly scattered throughout the domain of the output. Under these conditions and the assumptions underlying the HDMR it is argued that the number of samples needed for representation to a given tolerance is invariant to the dimensionality of the function, thereby providing for a very efficient means to perform high dimensional interpolation. Selected applications of HDMR's are presented from sensitivity analysis and time-series analysis.     

三电子原子的超球坐标分析和基态能态计算

用超球坐标表示多电子原子的薛定谔方程,从符合Pauli原理的全反称波函数出发,推导出相应的超球径耦合微分方程,其形式与双电子原子的相似。以九维超球谐为投影函数构造S₃群不可约表示的对称基,将超球谐-广义Laguerre展开法(HHGL)推广到Li原子,首次对其Schrdinger方程的精确求解进行了研究,基态能量的计算值与实验值接近。最后,还从波函数出发对提高计算的精度进行了讨论。     

构建光谱学精度的从头算偶极矩函数的基组依赖性

最近,人们对使用理论方法构建偶极矩函数给予了更多关注. 然而,构建偶极矩函数的计算方法并没有像势能面的计算方法那样得到充分测试. 本文以Ar-He为例,测试了如何用从头算方法构建达到光谱学精度的偶极矩函数. 特别关注了基组依赖性,即偶极矩函数随基组大小、基组叠加误差和键函数的收敛性. 本文还测试了显相关的方法在构建偶极矩函数的表现,相比传统方法,显相关方法在更小的基组即可收敛. 本文为使用不同从头算方法构建偶极矩函数提供了直观的对比.     

Combined bond-polarization basis sets for accurate determination of dissociation energies

Summary The effect of bond functions on the basis set superposition error (BSSE) is investigated at both SCF (self consistent field) and correlated levels for a number of basis sets using the pairwise additive function counterpoise (PAFC), the site-site function counterpoise (SSFC), and the newly proposed successive reaction counterpoise method (SRCP). BSSEs using bond functions are shown to be roughly twice those without bond functions, whereas the latter may still be quite sizeable. The addition of f functions dramatically decreases the bond function BSSE. The results obtained support the empirical decision in our earlier papers to neglect BSSE altogether.