Theoretical calculations are contributing a significantly higher proportion of data to contemporary spectroscopic databases, which have traditionally relied on experimental observations and semi-empirical models. It is now a common procedure to extend calculated line lists to include ro-vibrational transitions between all bound states of the ground electronic state up to the dissociation limit. Advanced ab initio methods are utilized to calculate the potential energy and dipole moment surfaces (PESs and DMSs), and semi-empirical PESs are then obtained by combining ab initio and experimental data. The objective is to reach high accuracy in the calculated transition intensities for all parts of spectrum, i.e. to increase the predictive power of the model. We show that in order to perform this task, one needs, in addition to the standard improvements of the PES and DMS in the spectroscopically accessible regions, to extend the ab initio calculations of the PES towards the united-atom limit along the stretching coordinates. The argument is based on the correlation between the intensities of high-overtone transitions and the repulsive potential wall that has previously been theoretically established for diatomic molecules and is empirically extended here to linear and nonlinear triatomic molecules. We generate partial line lists for water and ozone, and together with an already available line list for carbon dioxide, we derive the normal intensity distribution, which is a direct consequence of this correlation. The normal distribution is not an instrument to compute highly accurate intensities, rather it is a means to analyse the intensities computed by the traditional methods.

理论计算在当代光谱数据库中贡献了更高比例的数据，而传统光谱数据库通常依赖于实验观察和半经验模型。现在，通常的方法是扩展计算的线列表，以包括在地面电子状态的所有绑定状态之间直至解离极限的旋转振动转换。利用先进的从头算方法来计算势能和偶极矩表面（PES和DMS），然后通过组合从头算来获得半经验PES。和实验数据。目的是在频谱的所有部分的计算跃迁强度中达到高精度，即增加模型的预测能力。我们表明，为了执行此任务，除了在光谱可访问区域中对PES和DMS进行标准改进之外，还需要扩展从头开始。沿拉伸坐标向PES极限计算PES。该论据基于高泛音跃迁强度与排斥势垒之间的相关性，该势垒先前已在理论上为双原子分子建立，并在此经验扩展至线性和非线性三原子分子。我们生成水和臭氧的部分线列表，以及已经存在的二氧化碳线列表，我们得出正态强度分布，这是这种相关性的直接结果。正态分布不是计算高精度强度的工具，而是分析传统方法计算的强度的一种手段。