A refined potential energy surface and the rovibrational states for the electronic ground state of ozone

A potential energy surface for the electronic ground state of ozone has been optimized by using a variational procedure with the exact vibrational Hamiltonian in bond length-bond angle coordinates. In the optimization, the ab initio force field of Borowski, P., Andersson, K., Malmquist, P.-A., and Roos, B. O., 1992, J. chem. Phys., 97, 5568 is taken as the starting point, and the recent observed vibrational band origins up to 4900 cm^-1 reported by Floud, J.-M., Barbe, A., Camy-Peyret, C., and Plateaux, J. J., 1996, J. molec. Spectrosc., 177, 34 are involved. The root mean square error of this fit for the 39 observed vibrational energy levels is 0.83 cm^-1. In order to test the refined potential, the rovibrational energy levels up to J = 15 are calculated and compared with the observed values.     

利用多光子跃迁控制基态HF分子布居转移

采用波包动力学方法研究了HF分子基电子态的多光子跃迁. 激光场由两束频率比为1:2的重合红外脉冲构成. 态|0,0>作为初始态, 态|4,0>与态|4,2>分别作为目标态. 计算结果表明, 通过选取不同的共振频率, 可以控制布居跃迁至不同的目标态. 两束脉冲间的初相位差可以控制布居转移概率. 当初相位差为π/2的偶数倍时, 布居转移概率为最大值. 当初相位差为π/2的奇数倍时, 布居转移概率为最小值. 初相位差对于态|4,0>的布居影响大于态|4,2>. 关键词： 多光子跃迁 初相位 布居转移 波包     

Magnetic moment and electric quadrupole moment of the anomalous186Ir ground state

The ground state nuclear moments of¹⁸⁶Ir (j ^π=5⁽⁺⁾) have been determined with NMR on oriented¹⁸⁶Ir in Ni as |μ|=3.80 _?0.02 ^+0.12 μ _n andQ=?3.00 (15)b. The quadrupole moment is consistent with an anamolousj ^π K=5⁺0 or 5⁺1 ground state configuration. The explanation of the magnetic moment in terms of pure 5⁺0 or 5⁺1 configurations would require a high collectiveg _R-factor ofg _R≧0.76. On the other hand the magnetic moment can be explained with a “normal”g _R and a mixed ground state configuration.     

A refined potential energy function for the electronic ground state of H2Se

The potential energy surface for the electronic ground state of the hydrogen selenide molecule has been determined previously by Jensen and Kozin [J. Mol. Spectrosc. 160 (1993) 39] in a fitting to experimental data by means of the MORBID computer program. We report here a further refinement of this surface, also made with the MORBID program. With the refined potential surface, we can make predictions of rotation-vibration transition wavenumbers for H₂Se, D₂Se, and HDSe, and with these predictions we can assign weak spectra of these molecules. We assign here two very weak bands of HD⁸⁰Se, ν₁+ν₂+ν₃ and 2ν₁+ν₃. The refinement of the potential energy surface was made possible because (1) the number of vibrational states characterized experimentally for various isotopomers of H₂Se has approximately doubled since 1993, and (2) we now have access to larger computers with which we can fit energy spacings of states with J?8, whereas Jensen and Kozin could only use J?5. In the present work, we fitted rotation-vibration energy spacings associated with 24 vibrational states of H₂⁸⁰Se with v₁?6, v₂?3, and v₃?2; 11 vibrational states of D₂⁸⁰Se with v₁?2, v₂?3, and v₃?2, and 17 vibrational states of HD⁸⁰Se with v₁?3, v₂?3, and v₃?3. The input data set comprised 3611 energy spacings. In the fitting, we could usefully vary 29 potential energy parameters. The standard deviation of the fitting was 0.12 cm⁻¹ and the root-mean-square deviation for 49 vibrational term values was 0.59 cm⁻¹.     

Nuclear magnetic moment of the 57Cu ground state

The nuclear magnetic moment of the ground state of (57)Cu(Iota(pi) = 3/2(-), T(1/2) = 196.3 ms) has been measured to be /mu((57)Cu)/ = (2.00 +/- 0.05)mu(N) using the beta-NMR technique. Together with the known magnetic moment of the mirror partner (57)Ni, the spin expectation value was extracted as = -0.078 +/- 0.13. This is the heaviest isospin mirror T = 1/2 pair above the (40)Ca region for which both ground state magnetic moments have been determined. The discrepancy between the present results and shell-model calculations in the full f p shell giving mu((57)Cu) approximately 2.4mu(N) and approximately 0.5 implies significant shell breaking at (56)Ni with the neutron number N = 28.     

Improved potential energy curve and vibrational energies for the electronic ground state of the hydrogen molecule

The potential energy curve for the electronic ground state of the hydrogen molecule has been recomputed for intermediate and large internuclear separations. for 2.4 ≤ R ≤ 8.0a.u. the previous potential energy curve has been improved. The largest improvement amounts to 5.5 cm^?1, and was obtained in the vicinity of R = 4.4a.u.. Using the new potential energy curve, and the adiabatic and relativistic corrections, the vibrational and rotational energy levels have been calculated for H₂, HD, and D₂. The deviations of the calculated energy levels G(v) of H₂ and D₂ from the observed values follow very closely the nonadiabatic corrections resulting from the Van Vleck formula.     

Nuclear magnetic moment of 57Cu ground state

The nuclear magnetic moment of the ground state of ⁵⁷Cu(I^π = 3/2^-, T_1/2 = 196.3 ms) has been measured to be |μ(⁵⁷Cu)| = (2.00 ±0.05) μ_N using the β-NMR technique. Together with the known magnetic moment of the mirror partner ⁵⁷Ni, the spin expectation value was extracted as = -0.78 ± 0.13. Discrepancy between present results and shell model calculations in the full fp shell implies significant shell breaking at ⁵⁶Ni with the neutron number N = 28.     

Variation of the electronic transition moment for the SnO molecule

The r-centroid method is used to find semiempirically the dependence of the electronic transition moment R_e on the internuclear separation for the principal system of the SnO molecule.     

A theoretical study of FeCN in the Δ electronic ground state

The three-dimensional potential energy and dipole moment surfaces for the electronic ground state ⁶Δ of FeCN have been computed at the MR-SDCI + Q + E_rel/[Roos ANO (Fe), aug-cc-pVQZ (C, N)] level of theory, where MR-SDCI means ‘multi-reference single and double excitation configuration interaction’ and ANO means ‘atomic natural orbital’. Based on these potential energy and dipole moment surfaces, the spectroscopic parameters, rovibronic energies, structural parameters, vibrational transition moments, and the wavenumbers and intensities of selected rotation-vibration transitions have been calculated. The equilibrium structure is linear with r_e(Fe-C) = 2.048 Å and r_e(C-N) = 1.168 Å, and the zero-point averaged structure is bent with 〈r(Fe-C)〉₀ = 2.082 Å, 〈r(C-N)〉₀ = 1.172 Å, and 〈∠(Fe-C-N)〉₀ = 170(5)°. At all the MR-SDCI + Q and the size-extensive multi-reference averaged quadratic coupled-cluster (MR-AQCC) levels of theory, with and without relativistic correction E_rel, that were employed in the present work, ⁶Δ FeCN is predicted to be slightly more stable than ⁶Δ FeNC. For example, the energy difference between the two isomers is approximately 150 cm⁻¹ at the highest level of theory employed, MR-AQCC + E_rel/[Roos ANO (Fe), aug-cc-pVQZ (C, N)] with zero-point energy correction. The electronic structure of ⁶Δ FeCN has also been compared with that of ⁶Δ FeNC. At present, no experimental spectroscopic data are available for ⁶Δ FeCN. It is hoped that the present work will stimulate experimental investigations of this molecule.     

The hyperfine quadrupole moment of muonium in the ground state

The quadrupole moment of the ground state of the μ⁺e^? atom is calculated to be (3m_em_μ)^?1; effects in a crystal are briefly discussed.     

The determination of the nuclear ground state and transition charge density from measured electron scattering data

The evaluation of elastic and inelastic electron scattering cross sections is discussed in terms of the Fourier-Bessel expansion of the nuclear ground state and transition charge density, respectively. The method allows one to deduce the charge distributions and the moments as well as the corresponding errors, which originate on the one hand from the uncertainties in the measured data and on the other hand from the lack of knowledge about the large-q behaviour of the form factors; these two contributions are determined separately. The method is described and proved with an evaluation of pseudodata and then applied to ²⁰⁸Pb cross sections. For this nucleus, detailed results concerning the possible structure of the charge density are presented.     

A theoretical study of TeOH in its electronic ground state

The ab initio multireference single- and double-excitation configuration interaction (MRD-CI) method has been used to calculate the potential surfaces for the six lowest-lying electronic states of the TeOH molecule. The ²A″ ground state is predicted to have a bent equilibrium geometry. The first excited state, ²A′, is calculated to lie 2695 cm⁻¹ above the ground state. The MORBID program package has been used for the rotation-vibration analysis of the electronic ground state, for which the term values of the fundamental levels are calculated as 582 cm⁻¹ for the Te-O stretching mode, 959 cm⁻¹ for the bending mode, and 3655 cm⁻¹ for the O-H stretching mode.     

On the magnetic dipole moment of the153Tb ground state

Temperature dependence of the angular distribution anisotropy of the 212·0 keV gamma-ray following the decay of¹⁵³Tb oriented in a gadolinium host was measured at temperatures from 16 to 70 mK. Magnetic dipole hyperfine splitting parameter a₀ for¹⁵³Tb(Gd) and magnetic dipole moment of the¹⁵³Tb ground state were estimated to be ¦a ₀¦1·2×10^–5 eV and ¦¦3·1 nuclear magnetons, respectively.Authors are indebted to Dr. N. A. Lebedev, Yu. V. Yushkewich and the staff of the JINR synchrocyclotron for the preparation of the¹⁵³Tb activity. The participation of Ing. L. Mare, J. Ferencei and S. I. Antonov in the measurements is also acknowledged.     

Potential energy curve of Be2 in its ground electronic state

The potential energy curve of Be₂ in its ground electronic state is constructed by morphing accurate MR-CI ab initio potentials from the literature to available experimental ro-vibrational data within the framework of the reduced potential curve (RPC) approach of Jen? and Plíva [Adv. At. Mol. Phys. 19 (1983) 265-307]. The resulting potential energy curves are in close harmony with experiment allowing thus for reliable prediction of the so-far experimentally unprobed part of the molecular potential energy function.     

Symmetry breakdown in ground state dissociation of HD+

Experimental studies of the dissociation of the electronic ground state of HD+ following ionization of HD by fast proton impact indicate that the H++D(1s) dissociation channel is more likely than the H(1s)+D+ dissociation channel by about 7%. This isotopic symmetry breakdown is due to the finite nuclear mass correction to the Born-Oppenheimer approximation which makes the 1ssigma state 3.7 meV lower than the 2psigma state at the dissociation limit. The measured fractions of the two dissociation channels are in agreement with coupled-channels calculations of 1ssigma to 2psigma transitions.     

CN~+离子电子结构和跃迁性质的理论研究

采用多组态参考相互作用方法和AV5Z-DK基组对CN~+离子的两个解离极限C~+(~2P_u)+N(~2D_u)和C~+(~2P_u)+N(~4S_u)下的X~1Σ~+、a~3Π、~1Δ和A~1四个电子态的势能曲线、永久偶极矩和振动能级进行了计算.为保证计算结果的精确性,在计算中考虑了Davidson修正.基于求得的势能曲线,数值求解一维径向薛定谔方程得到了各个电子态的光谱数据,并与实验值和已有的理论值吻合较好.除此之外,对A~1Π→X~1Σ~+和1~1Δ?A1~Π的跃迁性质进行了研究,同时通过跃迁的弗兰克-康登因子及辐射寿命,对CN~+离子激光冷却的可行性进行了分析.     

A theoretical investigation of electronic ground state of parent sulfur diimide

In this paper various properties of parent sulfur diimides (PSD) as the simplest member of sulfur diimides family have been considered using both DFT and ab initio methods employing correlation consistent basis set hierarchies. According to these calculations, EZ conformer is predicted to be the most stable conformer in accord with experimental observation, while its energy difference with ZZ conformer is completely minute. Comparison of microwave gas phase spectra and dense phase IR experimental data with theoretical calculations show a great coincidence. The properties of EE conformer have also been anticipated and its possible presence in dense phase have been discussed although no firm experimental data exists for this conformer. The possible pathways for interconversion between various conformers have been investigated and only two unimolecular type processes namely EZ ↔ EE and EZ ↔ ZZ interconversions have been established according to a pseudo-rotation mechanism as constituting the essential dynamic of system.     

Ab initio dipole moment and theoretical rovibrational intensities in the electronic ground state of PH3

We report a six-dimensional CCSD(T)/aug-cc-pVTZ dipole moment surface for the electronic ground state of PH₃ computed ab initio on a large grid of 10 080 molecular geometries. Parameterized, analytical functions are fitted through the ab initio data, and the resulting dipole moment functions are used, together with a potential energy function determined by refining an existing ab initio surface in fittings to experimental wavenumber data, for simulating absorption spectra of the first three polyads of PH₃, i.e., (ν₂, ν₄), (ν₁, ν₃, 2ν₂, 2ν₄, ν₂ + ν₄), and (ν₁ + ν₂, ν₃ + ν₂, ν₁ + ν₄, ν₃ + ν₄, 2ν₂ + ν₄, ν₂ + 2ν₄, 3ν₂, 3ν₄). The resulting theoretical transition moments show excellent agreement with experiment. A line-by-line comparison of the simulated intensities of the ν₂/ν₄ band system with 955 experimental intensity values reported by Brown et al. [L.R. Brown, R.L. Sams, I. Kleiner, C. Cottaz, L. Sagui, J. Mol. Spectrosc. 215 (2002) 178-203] gives an average absolute percentage deviation of 8.7% (and a root-mean-square deviation of 0.94 cm⁻¹ for the transition wavenumbers). This is very remarkable since the calculations rely entirely on ab initio dipole moment surfaces and do not involve any adjustment of these surfaces to reproduce the experimental intensities. Finally, we predict the line strengths for transitions between so-called cluster levels (near-degenerate levels formed at high rotational excitation) for J up to 60.     

Self-consistent electronic structure and ground state properties of TlCl

We present the first self-consistent, relativistic, ab initio calculation of the electronic structure, equilibrium lattice constant, cohesive energy and compressibility of TlCl, as an example of a semiconductor with high atomic number and high ionicity. The theoretical approach is based on the local density-formalism. Our results explain the salient features of recent photoemission measurements and describe the ground-state properties with good accuracy.