Electronic state and potential energy function for UH^2＋

Our theoretical study on UH^{2+}( X^4Σ) using a density functional method shows that its potential energy curve has both minimum and maximum, which is the so-called "energy trapped" molecules. This sort of potential maximum is mainly caused by Coulomb repulsion. We have proposed the perturbation effect of ionic charges to explain the existence of the potential maximum for diatomic ions, and derived an analytic potential energy function has been derived, and the force constants and spectroscopic data are obtained. Finally, the vertical ionization potential for UH^{2+} has been calculated as well.     

Accurate studies on the full vibrational energy spectra and molecular dissociation energies for some electronic states of halogen molecule

This paper obtains accurate vibrational spectroscopic constants and full vibrational energy spectrum by the algebraic method (AM) for some electronic states of halogen diatomic molecules.Motivated by the recent success of obtaining the dissociation energies of Li 2 molecule by using a new analytical formula,it further extends the formula to study the dissociation energies of halogen diatomic molecules.The results show that the AM spectrum and the theoretical dissociation energies agree well with RKR data and experimental data respectively.     

Potential energy curve study on the ^3Π electronic states of GaX （X=F,Cl, and Br） molecules

The potential energy curves （PECs） of the 3Π states of GaX （X=F, Cl, and Br） molecules are calculated using the multireference configuration interaction method with a large contracted basis set aug-cc-pV5Z. The PECs are accurately fitted to analytical potential energy functions （APEFs） using the Murrell–Sorbie potential function. The spectroscopic parameters for the states are determined using the obtained APEFs, and compared with the theoretical and experimental data available presently in the literature.     

Potential energy curves and analytical potential energy functions of the metastable states of B2^＋＋

The multi-reference configuration interaction method and aug-cc-pvqz （AVQZ） have been used to calculate potential energy curves （PECs） of the singlet and triplet states of the riu and rig symmetry of B2＋＋. All of the four states （^l∏u, ^1∏g, ^3∏u and ^3∏g） are found to be metastable states, though the potential well of ^3∏u symmetry is very shallow. Based on the PECs, the analytical potential energy functions （APEFs） of these states have been fitted using the least square fitting method and two models of function. The spectroscopic parameters of each state are also calculated, and are compared with other investigations in the literature. The credibility and veracity of the two functions are evaluated. Some ideas to improve the fitting accuracy are presented. Also the vibrational levels for each state are predicted by solving the SchrSdinger equation of nuclear motion.     

The characteristics of doubly and triply charged ions C2^2＋, C2^2- and C2^3＋

Based on group theory and atomic and molecular reaction statics, this paper derives the possible electronic states of C^{2+}_2, C^{2-}_2 and C^{3+}_2, and their reasonable dissociation limits and determines their ground electronic states C^{2+}_2(X^3Π_u), C^{2-}_2(X^1Σ^+_g) and C^{3+}_2(X^4Σ^-_u) using quantum mechanical calculations at the level of QCISD/6-311G^*. All the potential energy curves of their ground states have both a minimum and a maximum, which are the so-called "energy trapped" molecules. This sort of potential maximum is chiefly due to Coulomb repulsion. We propose the perturbation effect of ionic charges, which is used to explain why the orbital degeneracy of diatomic ions may be removed. The characteristics of potential curves for diatomic ions are briefly described.     

Approximate analytical solutions and mean energies of stationary Schr¨odinger equation for general molecular potential

The Schrodinger equation is solved with general molecular potential via the improved quantization rule.Expression for bound state energy eigenvalues, radial eigenfunctions, mean kinetic energy, and potential energy are obtained in compact form. In modeling the centrifugal term of the effective potential, a Pekeris-like approximation scheme is applied. Also, we use the Hellmann–Feynman theorem to derive the relation for expectation values. Bound state energy eigenvalues, wave functions and meanenergies of Woods–Saxon potential, Morse potential, Mobius squared and Tietz–Hua oscillators are deduced from the general molecular potential. In addition, we use our equations to compute the bound state energy eigenvalues and expectation values for four diatomic molecules viz. H_2, CO, HF, and O_2. Results obtained are in perfect agreement with the data available from the literature for the potentials and molecules. Studies also show that as the vibrational quantum number increases, the mean kinetic energy for the system in a Tietz–Hua potential increases slowly to a threshold value and then decreases. But in a Morse potential, the mean kinetic energy increases linearly with vibrational quantum number increasing.     

团簇离子在固体中能损的非线性效应

研究了每核子能量为 2 6 0— 4 5 0keV的H₊2,H₊3,H₊4 H₊5和H₊7团簇离子在金膜中的能损 .发现团簇离子中平均每个质子的能损大于相同速度的单质子能损 ,即能损比大于 1,且随团簇离子的大小和速度的增加而增加. The energy losses of cluster ions H₊2,H₊3,H₊4 H₊5 and H₊7with energy of 260-450 keV/p in solid films have been measured. It has been found that the energy loss per proton in clusters is larger than that of single proton with the same velocity as clusters, that is, the energy ratio is larger than 1. Energy ratio increases with increasing the cluster size and velocity.     

The splitting of low-lying or low excited states for hydride molecules （cations） of the third period under spin-orbit coupling

This paper reports that the splitting of potential energy curves for the low-lying or low excited states for hydride molecules （cations） （MgH, AlH^＋, SiH, PH^＋, SH,ClH^＋） of the third period under Spin-Orbit Coupling has been calculated by using the Spin-Orbit Multi-Configuration Quasi-Degenerate Perturbation Theory （SO-MCQDPT） method. Then, spectroscopic constants of the split states have been derived from the Murrell-Sorbie function. The calculated dissociation energies for the spectrum branch terms have been given, respectively. The spectroscopic constants and dissociation energies for the spectrum branch terms are given for the first time in this paper.     

The molecular structure and the analytical potential energy function of S2^- and S3^-

In this paper, the equilibrium geometry, harmonic frequency and dissociation energy of S2^- and S3^- have been calculated at QCISD/6-311＋＋G（3d2f） and B3P86/6-311＋＋G（3d2f） level. The S2^- ground state is of 2IIg, the S3^- ground state is of 2B1 and S3^- has a bent （C2v） structure with an angle of 115.65° The results are in good agreement with these reported in other literature. For S3^- ion, the vibration frequencies and the force constants have also been calculated. Base on the general principles of microscopic reversibility, the dissociation limits has been deduced. The Murrell-Sorbie potential energy function for S2^- has been derived according to the ab initio data through the least- squares fitting. The force constants and spectroscopic data for S2^- have been calculated, then compared with other theoretical data. The analytical potential energy function of S3^- have been obtained based on the many-body expansion theory. The structure and energy can correctly reappear on the potential surface.     

MRCI potential energy curves and analytical potential energy functions for the X^2∑^＋ and 2^∏ states of BO molecule

The potential energy curves （PECs） of BO molecule, including ∑^＋and ∏ symmetries with doublet spin multiplicities, are obtained employing multi-reference configuration interaction （MRCI） method and Dunning＇s correlation consistent basis sets. The analytical potential energy functions （APEFs） are fitted using the Murrell-Sorbie （MS） function and the least square method. Based on the PECs, the spectroscopic constants of the states have been determined and compared with the theoretical and experimental results available to affirm the accuracy and liability of the calculations. The root-mean-square （RMS） errors between the fitted results and the ab initio values are too little in comparison with the chemical accuracy （349.755 cm^-1）. It is shown that the present APEFs are accurate and can display the interaction between the atoms well. The present APEFs can be used to construct more complicated APEF or do some dynamic investigations.     

Separation of Deuterium Isotope by Chemical Exchange between Hydrogen and Water Vapour

The separation factor of deuterium (α) for the exchange reaction between hydrogen and water vapour at 100 °C has been measured and was found to be equals to 2.52 and 2.50, depending on the used experimental technique.

An empirical equation relating the variation of the separation factor with temperature for such isotopic exchange reaction has been deduced. The values of α were calculated from 0–800 °C and indicated close agreement with those calculated from spectroscopic data.

Comparison of the deduced empirical equation with the general equation relating the separation factor with temperature for such reaction, allowed the calculation of the zero point energy, as well as the free energy as a function of temperature.     

Density and thermodynamics of hydrogen adsorbed on the surface of single-walled carbon nanotubes

A method is proposed for calculating the adsorption of hydrogen in single-walled carbon nanotubes. This method involves solving the Schrödinger equation for a particle (hydrogen molecule) moving in a potential generated by the surrounding hydrogen molecules and atoms forming the wall of the carbon nanotube. The interaction potential for hydrogen molecules is taken in the form of the Silvera-Goldman empirical potential, which adequately describes the experimental data on the interaction between H₂ molecules (including the van der Waals interaction). The interaction of hydrogen molecules with carbon atoms is included in the calculation through the Lennard-Jones potential. The free energy at a nonzero temperature is calculated with allowance made for the phonon contribution, which, in turn, makes it possible to take into account the correlations in the mutual arrangement of the neighboring molecules. The dependences of the total energy, the free energy, and the Gibbs thermodynamic potential on the applied pressure P and temperature T are calculated for adsorbed hydrogen molecules. These dependences are obtained for the first time with due regard for the quantum effects. The pressure and temperature dependences of the hydrogen density m(P, T) are also constructed for the first time.     

氢及其同位素分子的电子碰撞解离反应截面研究

在边界等离子体中氢及其同位素分子与电子碰撞可以发生解离反应。对于尚无反应截面的氢及其同位素分子电子碰撞激发到三重态然后发生解离反应,作者基于莫尔斯函数、弗兰克－康登原理,采用半经典的Gryzinski方法计算了这一反应截面。得到了解离反应截面的影响因素、反应截面随电子能量的变化情况以及分子的振动能级对反应截面的影响。通过比较表明到排斥态的激发然后发生解离反应的反应截面占据主导地位,比激发到其它三重态激发然后发生解离的反应截面要大一个量级。     

Isotope effect on the stereodynamics for the collision reaction H＋LiF（v = 0, j = 0） → HF＋Li

Stereodynamics for the reaction H+LiF(v=0, j=0) → HF+Li and its isotopic variants on the ground-state (1 2 A′) potential energy surface (PES) are studied by employing the quasi-classical trajectory (QCT) method. At a collision energy of 1.0 eV, product rotational angular momentum distributions P (θr), P (φr), and P (θr ,φr), are calculated in the center-of-mass (CM) frame. The results demonstrate that the product rotational angular momentum j′ is not only aligned along the direction perpendicular to the reagent relative velocity vector k, but also oriented along the negative y axis. The four generalized polarization-dependent differential cross sections (PDDCSs) are also computed. The PDDCS 00 distribution shows a preferential forward scattering for the product angular distribution in each of the three isotopic reactions, which indicates that the title collision reaction is a direct reaction mechanism. The isotope effect on the stereodynamics is revealed and discussed in detail.     

采用量子波包方法和准经典轨线方法研究S(~3P)+HD反应

利用量子波包方法和准经典轨线方法在一个新的3A′′势能面上研究了S(3P)+HD→SD+H和SH+D反应的动力学性质.计算得到了两个反应通道在碰撞能为0.8—2.2 eV范围内的J=0反应几率、积分反应截面、内同位素因子和产物转动取向因子.这些结果揭示了S(3P)+HD反应非常明显的内同位素效应.通过对势能面和反应轨线的分析,我们发现了SD+H反应通道一个新的反应机制.S(3P)+HD反应的内同位素效应可以利用新发现的反应机制和反应的质量组合来进行解释.     

用CCSD(T)方法计算基态SH和SD的光谱常数(英文)

利用CCSD(T)方法和系列相关一致基cc-pVXZ及aug-cc-pVXZ(X=D,T,Q,5)对SH和SD分子的基态平衡几何,谐振频率和离解能进行了优化计算.利用优选出的CCSD(T)/aug-cc-pV5Z方法对SH和SD的基态进行单点能计算,并将计算结果拟合成了Murrell-Sorbie函数.利用得到的解析势能函数,计算了SH和SD的其余3个光谱常数(ω_ex_e,α_e和B_c),结果表明:除SD的ω_ex_e值外,其余结果均与实验值符合得相当好,但计算得出的ω_ex_e值与推导出的值25.134 cm~(-1)符合得很好.     

六参数高精度双原子分子解析势能函数

提出一种构造解析势能函数的新方法,得到一种六参数解析势能函数,该势能函数适用于多种基本类型的双原子分子.用同核中性基态双原子分子Li₂-X¹Σ_g⁺、Na₂-X¹Σ_g⁺,异核带电基态双原子分子离子(BC)^--X³∏,异核中性激发态双原子分子PbS-A¹Σ⁺、BaO-A¹Σ,异核带电激发态双原子分子离子(CS)⁺-A²∏,同核中性激发态双原子分子K₂-B¹∏_u,同核带电激发态双原子分子离子N₂⁺-B²Σ_u⁺等共36个算例对该势能函数进行验证,计算结果与RKR(Rydberg-Klein-Rees)数据或振动能谱实验数据高精度符合.同时发现,在分子振动能谱计算精度方面,该势能函数总体上优于Murrell-Sorbie势能函数.     

密度泛函理论研究LiX(X=H,D,T)体系的热力学性质

运用量子力学从头计算方法,计算了氢化锂(氘化锂、氚化锂)分子的部分热力学函数和力学、光谱学性质。基于准简谐Debye模型,计算了固体Li的振动内能、振动和电子熵,探讨了Li吸收氢同位素气体生成一氢化物的反应熵变、生成焓变和生成Gibbs自由能及氢同位素的平衡离解压。结果显示:在Li吸收同位素气体生成一氢化物的反应中,生成焓变和反应熵变均为负值,且随温度升高,绝对值越大,Gibbs自由能则向正的方向增加。热力学上,在相同温度和压力下,氢置换一氢化物中的氘和氚、及氘置换氚的反应更易发生。     

氦同位素与氢分子碰撞的振转激发分波截面研究

用密耦近似方法和Tang-Toennies势模型计算了E=0·7eV时,氦原子的四种同位素3He,4He,9He,10He与氢分子H2碰撞体系的振转激发分波截面.通过分析各碰撞体系分波截面的差异,探讨了He(3He,4He,9He,10He)-H2碰撞体系的弹性碰撞、纯转动激发和振转激发情况下,其分波截面随量子数和体系约化质量的变化规律.     

载能氢同位素原子与石墨(001)面碰撞的分子动力学研究

采用分子动力学方法研究了载能H同位素原子与石墨晶体碰撞的同位素效应. 碳氢系统的强共价键作用和石墨层间的弱van der Waals力分别用REBO和Ito半经验势函数来描述. 研究发现: 随着入射原子质量的增加, 上表面吸附几率和反射几率的峰值都会向高能区移动; 相比于H, ²H入射原子, ³H入射原子具有较高的吸附几率——包括上表面吸附和内部吸附; 穿透石墨晶体, ²H, ³H原子所需的能量较高; 原子质量和原子入射能量都会影响入射粒子与不同石墨层之间的能量传递过程. 这些结果对理解碳基材料的³H滞留机制有重要意义.