Accurate ab initio potential energy curve of O2. II. Core-valence correlations, relativistic contributions, and vibration-rotation spectrum.
Accurate ab initio potential energy curve of O2. II. Core-valence correlations, relativistic contributions, and vibration-rotation spectrum.
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DOI：
10.1063/1.3298376
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
L. Bytautas;N. Matsunaga;K. Ruedenberg
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文献类型：
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作者：
L. Bytautas;N. Matsunaga;K. Ruedenberg
在这一系列的第一篇论文中，在所有价壳电子关联都是在完全基组极限下计算的近似下，确定了O(2)的(3)Sigma(G)(-)基态的非常精确的从头算势能曲线。在本研究中，确定了由核心电子关联和相对论效应，即自旋-轨道耦合和标量相对论引起的修正，并将其添加到势能曲线中。根据这条曲线上计算的24个点，确定了均匀调和高斯函数的解析表达式，并用离散变量表示法从它计算了振动和转动能级。我们发现了42个振动能级。实验数据(来自Schumann-Runge带系统)只产生最低的36个能级，这是因为较高能级的跃迁强度显著降低。对于35个项值G(V)，理论值与实验值的平均绝对偏差为12.8 cm(-1)。解离能与最低振动能的关系在实验值41,268.2+/-3 cm(-1)的25 cm(-1)范围内计算。发现(3)Sigma(G)(-)态和(1)Sigma(G)(+)态之间的理论交叉发生在2.22A处，并分析了该区域的自旋-轨道耦合。
In the first paper of this series, a very accurate ab initio potential energy curve of the (3)Sigma(g)(-) ground state of O(2) has been determined in the approximation that all valence shell electron correlations were calculated at the complete basis set limit. In the present study, the corrections arising from core electron correlations and relativity effects, viz., spin-orbit coupling and scalar relativity, are determined and added to the potential energy curve. From the 24 points calculated on this curve, an analytical expression in terms of even-tempered Gaussian functions is determined and, from it, the vibrational and rotational energy levels are calculated by means of the discrete variable representation. We find 42 vibrational levels. Experimental data (from the Schumann-Runge band system) only yield the lowest 36 levels due to significant reduction in the transition intensities of higher levels. For the 35 term values G(v), the mean absolute deviation between theoretical and experimental data is 12.8 cm(-1). The dissociation energy with respect to the lowest vibrational energy is calculated within 25 cm(-1) of the experimental value of 41,268.2+/-3 cm(-1). The theoretical crossing between the (3)Sigma(g)(-) state and the (1)Sigma(g)(+) state is found to occur at 2.22 A and the spin-orbit coupling in this region is analyzed.