Abstract A set of permutationally invariant potential energy surfaces for the electronic ground state of formaldehyde is built at several levels of electronic theory and atomic orbital basis sets starting from a database of more than 34,000 ab initio energies. Preliminarily, the reliability of the fitted surfaces is determined by comparing the calculated harmonic frequencies with the corresponding ab initio values. Then, semiclassical estimates of the quantum frequencies of vibration are presented, and their dependence on the employed level of theory, type of atomic orbital basis set, and complexity of the fit is investigated. Comparisons of semiclassical results to experimental data provide a further assessment of the quality of the analytical surfaces and show that anharmonic frequencies are influenced by the precision of the fit, while accurate frequency values are obtained also with density functional theory. Results and conclusions support the use of ab initio “on-the-fly” semiclassical dynamics as a means of spectroscopic investigation when high-level analytical potential energy surfaces are not available.

中文翻译：

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半经典振动光谱对势能表面精度的敏感性：甲醛测试

摘要 从包含 34,000 多个 ab initio 能量的数据库开始，在电子理论和原子轨道基组的多个层次上构建了一组甲醛电子基态的置换不变势能面。初步地，拟合表面的可靠性是通过将计算的谐波频率与相应的 ab initio 值进行比较来确定的。然后，介绍了振动的量子频率的半经典估计，并研究了它们对所采用的理论水平、原子轨道基组类型和拟合复杂性的依赖性。半经典结果与实验数据的比较提供了对分析表面质量的进一步评估，并表明非谐波频率受拟合精度的影响，同时还可以通过密度泛函理论获得准确的频率值。结果和结论支持使用 ab initio “on-the-fly” 半经典动力学作为光谱研究的手段，当高级分析势能面不可用时。