The EF and GK 1Σg+ states of hydrogen: Adiabatic calculation of vibronic states in H2, HD, and D2
The EF and GK 1Σg+ states of hydrogen: Adiabatic calculation of vibronic states in H2, HD, and D2
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氢的 EF 和 GK 1Σg+ 态：H2、HD 和 D2 中振动态的绝热计算
DOI：
10.1016/0022-2852(77)90050-9
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发表时间：
1977
影响因子：
1.4
通讯作者：
K. Dressler
中科院分区：
文献类型：
--
作者：
L. Wolniewicz;K. Dressler
摘要 氢的前两个 1 Σ g+ 激发态 EF 和 GK 的玻恩-奥本海默能量的计算精度比以前更高（70 项波函数），且 R 范围更大（1 au< R≤ 15 au）。对于第三激发 1 Σ g+ 态 H，在相同的大 R 范围内也给出了不太准确的结果，发现其势曲线在 R= 11 au 附近表现出宽而平坦的外部最小值 H，与第三 1 Σ u+ 态 B 中的类似。GK 态中核运动的对角线修正以及 EF 和 GK 势中振动态的能量和 B 值在绝热近似中计算，直到解离极限。 GK 势垒曲线有两个最小值，每个最小值容纳一个振动能级，而所有其他能级都位于势垒之上。这些从头计算的结果忽略了不同电子态之间核动量耦合的影响，但与实验数据惊人地一致，尽管电子 GK 波函数在最低振动能级的 R 范围内（即势垒区域和外部最小值区域）经历了两次明显的特征变化。所有通过实验建立的、不规则的 H 2 单重态 g 能级（由理查森和 Dieke 赋予电子标签 Q、3K、3D、L、M、U 和 N）现在都可以归因于两个电子玻恩-奥本海默态 EF 和 GK，这两种电子振动-旋转结构都具有双极小势能曲线的特征。实验能级揭示了扰动，其定量解释需要对振动电子态进行非绝热计算；这种治疗的结果将单独介绍。在第一篇论文中，我们对有关 1 Σ g+ 态内这些电子振动相互作用的大小以及电子运动与核旋转之间的耦合（即 1 Σ g+-1 Π g-1 Δ g 相互作用（l-解耦））的实验证据进行了初步调查。
Abstract The Born-Oppenheimer energies of the first two excited 1 Σ g+ states of hydrogen, EF and GK, are computed with higher accuracy (70-term wavefunctions) and over larger R ranges (1 au< R≤ 15 au) than previously available. Less accurate results over the same large R range are also presented for the third excited 1 Σ g+ state, H, whose potential curve is found to exhibit a broad and flat outer minimum, H, near R= 11 au, similar to the one in the third 1 Σ u+ state, B. The diagonal corrections for nuclear motion in the GK state and the energies and B values of the vibrational states in the EF and GK potentials are computed in the adiabatic approximation up to the dissociation limit. The GK potential curve has two minima, each of which accommodates one single vibrational level, while all other levels lie above the potential barrier. These ab initio results, in which the effects of nuclear-momentum coupling between different electronic states are neglected, agree surprisingly well with experimental data although the electronic GK wavefunction goes through two marked changes of character within the R range of the lowest vibrational levels, viz., in the regions of the potential barrier and of the outer minimum. All of the experimentally established and irregular singlet-g levels of H 2, which had been given electronic labels Q, 3K, 3D, L, M, U, and N by Richardson and by Dieke, can now be attributed to the two electronic Born-Oppenheimer states EF and GK, both of whose vibration-rotation structures are characterized by double-minimum potential curves. The experimental energy levels reveal perturbations whose quantitative explanation requires nonadiabatic computations of rovibronic states; results of such a treatment will be presented separately. In this first paper we include a preliminary survey of the experimental evidence regarding the magnitudes of these vibronic interactions within the 1 Σ g+ states and of the coupling between electronic motion and nuclear rotation, ie, 1 Σ g+-1 Π g-1 Δ g interactions (l-uncoupling).