BH分子X 1Σ+、A 1Π和B 1Σ+ 态的势能函数

利用SAC/SAC-CI方法，使用D95++、6-311++g及cc-PVTZ等基组，对BH分子的基态(X ¹Σ⁺)、第一简并激发态(A ¹Π)及第二激发态(B ¹Σ⁺)的平衡结构和谐振频率进行了优化计算． 通过对三个基组计算结果的比较，得出了cc-PVTZ基组为三个基组中的最优基组的结论；使用cc-PVTZ基组，利用SAC的GSUM(group sum of operators)方法对基态(X ¹Σ⁺)， SAC-CI的GSUM方法对激发态(A ¹Π 和B ¹Σ⁺)进行单点能扫描计算, 用正规方程组拟合Murrell-Sorbie函数，得到了相应电子态的完整势能函数；从得到的势能函数计算了与基态(X ¹Σ⁺)、第一简并的激发态(A ¹Π)和第二激发态(X ¹Σ⁺)相对应的光谱常数(Be、αe、ωe 和ωeχe)，结果与实验数据较为一致． 其中基态、第一激发态与实验数据吻合得较好．     

BF分子X~1Σ~+,A~1Π和B~1Σ~+电子态的势能函数

使用SAC/SAC-CI和D95++,6-311++g,6-311++g**及D95(d)基组,分别对BF分子的基态X~1Σ~+、第一简并激发态A~1Π和第二激发态B~1Σ~+的平衡结构和谐振频率进行优化计算.对所有计算结果进行比较,得出6-311++g**基组为最优基组.运用6-311++g**基组和SAC方法对基态X~1Σ~+,SAC-CI方法对激发态A~1Π和B~1Σ~+进行单点能扫描计算,并用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由得到的势能函数计算了与X~1Σ+,A~1Π和B~1Σ~+态相对应的光谱常数,结果与实验数据较为一致.     

New self-consistent potentials for the X1Σ+ and A1Σ+ states of KH

The vibrational and rotational molecular constants have been determined for the A¹Σ⁺  X¹Σ⁺ system of the isotopic potassium hydrides: KH and KD. From these experimental term values, isotopically combined PMO-RKR-van der Waals potentials are constructed, which are checked by direct integration of radial Schrödinger equation. As an additional check on the accuracy of the potentials, the wavefunctions were used to compute B_ν, D_ν, H_ν and L_ν values. The agreement between the calculated and experimental results is quite satisfactory. Franck-Condon overlap integrals and probability density distributions have been calculated. The anomalous behaviour of the A¹Σ⁺ state may be observed in the probability density functions of the lowest vibrational levels.     

Self-consistent potential energy curves for the A1Σ+ and X1Σ+ states of isotopic cesium hydrides

From the spectroscopic experimental data available in the literature we have determined the mass-reduced Dunham coefficients for the A¹Σ⁺ ↔ X¹Σ⁺ system of the isotopic species CsH and CsD. Based upon these results, for both ground and excited states of cesium hydride and deuteride we report new hybrid rotationless potential energy curves (PMO-RKR-van der Waals) up to the dissociation. As a consistency check on the accuracy of the potentials the eigenvalues were calculated by direct numerical integration of the radial Schrödinger equation and found to agree within the rms error 0.39 cm⁻¹ (X¹Σ⁺) and 0.41 cm⁻¹ (A¹Σ⁺) with the experimental vibrational energies. From the wavefunctions, the rotational constants B_υ, centrifugal distortion terms D_υ, H_υ and L_υ, Franck—Condon factors, and probability density distributions were obtained. The probability density distributions for the lowest vibrational levels of the A¹Σ⁺ show an anharmonicity associated with the anomalous behavior of that state.     

BF分子X1Σ＋, A1P和B1Σ＋态的势能函数

使用SAC/SAC-CI和D95＋＋, 6-311＋＋g, 6-311＋＋g**及D95(d)基组, 分别对BF分子的基态X¹Σ^＋、第一简并激发态A¹Π和第二激发态B¹Σ^＋的平衡结构和谐振频率进行优化计算. 对所有计算结果进行比较, 得出6-311＋＋g**基组为最优基组. 运用6-311＋＋g**基组和SAC方法对基态X¹Σ^＋, SAC-CI方法对激发态A¹Π和B¹Σ^＋进行单点能扫描计算, 并用正规方程组拟合Murrell-Sorbie函数, 得到相应电子态的势能函数解析式, 由得到的势能函数计算了与X¹Σ^＋, A¹Π和B¹Σ^＋态相对应的光谱常数, 结果与实验数据较为一致.     

Fourier spectrometry investigation of the 1 3Σg+ →a 3Σu+ transition of the 7Li2 molecule

The 1 ³Σ_g⁺ → a ³Σ_u⁺ transition in the ⁷Li₂ molecule has been observed in the 8200–10 000 cm⁻¹ region with a high resolution Fourier spectrometer. Rotational analysis of 1 ⩽ υ′ ⩽ 7 of 1 ³Σ_g⁺ and 0 ⩽ υ″ ⩽ 7 of a ³Σ_u⁺ has been carried out. We found D_e(a ³Σ_u⁺) = 332.5 ± 1.0 cm⁻¹ that gives T_e(a ³Σ_u⁺) = 8184.3 ± 1.5 cm⁻¹ and D_e(1 ³Σ_g⁺) = 7090.4 ± 1.5 cm⁻¹ with T_e = 16330 ± 2 cm⁻¹.     

Rotational analysis and deperturbation of the A2Π → X2Σ+ and B'2Σ+ → X2Σ+ emission spectra of MgH

Deperturbation analysis of the A(2)Π → X(2)Σ(+) and B(')(2)Σ(+) → X(2)Σ(+) emission spectra of (24)MgH is reported. Spectroscopic data for the v = 0 to 3 levels of the A (2)Π state and the v = 0 to 4 levels of the B'(2)Σ(+) state were fitted together using a single Hamiltonian matrix that includes (2)Π and (2)Σ(+) matrix elements, as well as off-diagonal elements coupling several vibrational levels of the two states. A Dunham-type fit was performed and the resulting Y(l,0) and Y(l,1) coefficients were used to generate Rydberg-Klein-Rees (RKR) potential curves for the A (2)Π and the B'(2)Σ(+) states. Vibrational overlap integrals were computed from the RKR potentials, and the off-diagonal matrix elements coupling the electronic wavefunctions (a(+) and b) were determined. Zero point dissociation energies (D(0)) of the A(2)Π and B'(2)Σ(+) states of (24)MgH were determined to be 12,957.5 ± 0.5 and 10,133.6 ± 0.5 cm(-1), respectively. Using the Y(0,1) coefficients, the equilibrium internuclear distances (r(e)) of the A(2)Π and B'(2)Σ(+) states were determined to be 1.67827(1) ? and 2.59404(4) A?, respectively.     

BH分子X~∑~+、A~1Ⅱ和B~1∑~+态的势能函数

利用SAC/SAC-CI方法,使用D95++、6-311++g及cc-PVTZ等基组,对BH分子的基态(X1撞+)、第一简并激发态(A1装)及第二激发态(B1撞+)的平衡结构和谐振频率进行了优化计算.通过对三个基组计算结果的比较,得出了cc-PVTZ基组为三个基组中的最优基组的结论;使用cc-PVTZ基组,利用SAC的GSUM(groupsumofoperators)方法对基态(X1撞+),SAC-CI的GSUM方法对激发态(A1装和B1撞+)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X1撞+)、第一简并的激发态(A1装)和第二激发态(B1撞+)相对应的光谱常数(Be、琢e、棕e和棕e字e),结果与实验数据较为一致.其中基态、第一激发态与实验数据吻合得较好.     

Accurate electrical and spectroscopic properties ofX 1Σ+ BeO from coupled-cluster methods

Summary This paper reports a series of coupled-cluster (CC) calculations through CCSDT on the theoretically challenging ground state of the BeO molecule. Along with CC methods, quadratic configuration interaction (QCI) approximations to CC theory have been used (QCISD and QCISD(T)), which show several dramatic failings. Equilibrium electrical properties (, _xx , and _zz ) and basic spectroscopic properties (r _e, _e,D _e, and infrared intensity (I)) have been computed. Basis set and electron correlation effects are analyzed in order to arrive at accurate values of the dipole moment and polarizability, which are not known experimentally. For the dipole moment, we obtain a value of 6.25 D, with an uncertainty of about 0.1 D. For _xx and _zz , we suggest respective values of 32 and 36 atomic units (a.u.) and error bars of about 1 and 2 a.u. With extended basis sets, the spectroscopic propertiesr _e, _e, andD _e are reproduced to high accuracy, which is the first time this has been achieved for this species byab initio methods. At the highest calculation levels,I is predicted to be very small. AlthoughI has not been measured, some support for this prediction comes from a recent infrared study of BeO-rare gas complexes. The QCI methods are shown to be much more sensitive to basis set, and even with large basis sets yield values of _zz andI which differ from CC results by an order of magnitude and three orders of magnitude, respectively. These differences doubtless arise from the importance of single excitations (T ₁) for this molecule, as several terms involvingT ₁ are neglected in the QCISD approximation compared with CCSD. We also report CC calculations with Brueckner orbitals, which yield results similar to those obtained with restricted Hartree-Fock orbitals.     

N2+分子离子的B2Σu+、A2Πu和X2Σg+电子态光谱研究

采用光外差-磁旋转-速度调制吸收光谱技术, 在可见光波段范围16800～17573 cm-1, 对N2+的A 2Πu-X 2Σ+g(12,6)、(11,5)、(7,2)带和B 2Σ+u-X 2Σ+g (1,5)带进行了测量和分析,推导了双原子分子振转能级在受到微扰作用时的有效哈密顿量形式,并分析了N2+的A 2Πu-B 2Σ+u之间存在的微扰相互作用,通过与实验数据的拟合得到了精确的电子态微扰常数ξe、ηe .     

BF分子X1∑+,A1∏和B1∑+电子态的势能函数

使用SAC/SAC-CI和D95++,6-311++g,6-311++g**及D95(d)基组,分别对BF分子的基态X1∑+、第一简并激发态A1∏和第二激发态B1∑+的平衡结构和谐振频率进行优化计算.对所有计算结果进行比较,得出6-311++g**基组为最优基组.运用6-311++g**基组和SAC方法对基态X1∑+,SAC-CI方法对激发态A1∏和B1∑+进行单点能扫描计算,并用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由得到的势能函数计算了与X1∑+,A1∏和B1∑+态相对应的光谱常数,结果与实验数据较为一致.     

传能反应O(1D)+CO2(1Σ+g)→O(3P)+CO2(1Σ+g)中间物机理的理论研究

利用ab initio 量子化学方法研究了自旋禁阻的传能反应O(1D)+CO2(1Σ+g)→O(3P)+CO2(1Σ+g)的反应机制, 通过中间化合物CO3的单、三重态的势能面交叉点的确认, 证明了中间物传能机理的可行性. 同时计算了交叉点处的自旋-轨道偶合和面间跃迁几率, 进一步证明了中间化合物CO3的形成在传能过程中的重要作用.     

Analysis of the D1 Δ—X1Σ+ transition in CO observed by two-photon excitation

The D¹ Δ—X¹Σ⁺ transition in carbon monoxide has been observed by two-photon excitation with a frequency-doubled pulsed dye laser. The rotational structure of thirteen υ′= 0 bands has been analyzed: the υ′= 6–12 bands in ¹²C¹⁶O, υ′= 7, 10 and 12 in ¹³C¹⁶O, and υ′= 7, 10 and 12 in ¹³C¹⁸O. Detailed assignments are presented, and from them the rotational and vibrational constants of the D¹ Δ state have been determined. Using a single mass-reduced fit, molecular constants are calculated for all three isotopomers. Analysis of the 7-0 band of the I¹Σ⁻−X¹Σ⁺ transition is also given.     

KH(KD)分子基态(X~1Σ~+)的结构与势能函数研究

利用群论及原子分子反应静力学的有关原理,推导了KH(KD)分子基态X1Σ+的电子态和合理的离解极限.采用Gaussian03程序包中的多种方法和基组,对KH(KD)分子基态X1Σ+的平衡结构和谐振频率进行了优化计算.通过比较计算结果,发现B3LYP为最优方法,6-311g(3df,3pd)为最佳基组.运用优选出的方法和基组对KH(KD)分子基态进行了单点势能扫描,然后分别采用Murrell-Sorbie函数及修正的Murrell-Sorbie+c6函数进行了非线性最小二乘拟合,得到了KH(KD)分子基态的势能函数和相应的光谱常数.计算结果表明,利用修正的Murrell-Sorbie+c6函数计算所得的光谱常数与实验数据吻合得更好.     

Adiabatic versus diabatic descriptions of the lowest Rydberg and valence 1Σ+ states of HCl

In this contribution we first report new ab initio self-consistent field configuration interaction calculations of the first excited adiabatic potential of (1)Σ(+) symmetry, the 2(1)Σ(+) or B(1)Σ(+) state, which presents two minima and can thus be seen as made up of the Rydberg E(1)Σ(+) and the valence V(1)Σ(+) states. Based on the computed 2(1)Σ(+) potential, we devised a theoretical procedure to compute the vibronic structure in order to try to explain the energy levels observed in the region above 76 254.4 cm(-1) which display an irregular vibrational structure, indicative of spectral perturbations. We try to find out which representation of the electronic states, the diabatic or the adiabatic one, is best suited to replicate the lowest observed vibronic levels of the E and V states. To this end, we deduce, from the 2(1)Σ(+) potential and its complementary adiabatic potential, two diabatic potentials. We then carry out a coupled equation treatment based on these diabatic potentials. The results of this treatment indicate that, in the present case, the adiabatic representation is better than the diabatic one to describe the observed vibronic levels. This is due, as expected, to the existence of a strong electrostatic interaction between the two diabatic potentials.     

Alignment effect of N2(A3Σu+) in the energy transfer reaction of aligned N2(A3Σu+) + NO(X2Π) → NO(A2Σ+) + N2(X1Σg+)

Steric effect in the energy transfer reaction of N(2)(A(3)Σ(u)(+)) + NO(X(2)Π) → NO(A(2)Σ(+)) + N(2)(X(1)Σ(g)(+)) has been studied under crossed beam conditions at a collision energy of ~0.07 eV by using an aligned N(2)(A(3)Σ(u)(+)) beam prepared by a magnetic hexapole. The emission intensity of NO(A(2)Σ(+)) has been measured as a function of the magnetic orientation field direction (i.e., alignment of N(2)(A(3)Σ(u)(+))) in the collision frame. A significant alignment effect on the energy transfer probability is observed. The shape of the steric opacity function turns out to be most reactive at the oblique configuration of N(2)(A(3)Σ(u)(+)) with an orientation angle of γ(v(R)) ~ 45° with respect to the relative velocity vector (v(R)), which has a good correlation with the spatial distribution of the 2pπ(g)* molecular orbital of N(2)(A(3)Σ(u)(+)). We propose the electron exchange mechanism in which the energy transfer probability is dominantly controlled by the orbital overlap between N(2)(2pπ(g)*) and NO(6σ).