Theoretical calculations of vibrational properties are widely used to explain and predict experimental spectra. However, with standard quantum chemical methods all molecular motions are considered, which is rather time-consuming for large molecules. Because typically only a specific spectral region is of experimental interest, we propose here an efficient method that allows calculation of only a selected frequency interval. After a computationally cheap low-level estimate of the molecular motions, the computational time is proportional to the number of normal modes needed to describe this frequency range. Results for a medium-sized molecule show a reduction in computational time of up to 1 order of magnitude with negligible loss in accuracy. We also show that still larger computational savings are possible by using an additional intensity-selection procedure.

中文翻译：

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振动频谱的频率范围选择方法。

振动特性的理论计算被广泛用于解释和预测实验光谱。但是，使用标准的量子化学方法，必须考虑所有分子运动，这对于大分子而言是相当耗时的。因为通常只有特定的频谱区域才是实验关注的问题，所以我们在这里提出一种有效的方法，该方法仅允许计算选定的频率间隔。在对分子运动进行计算廉价的低级估计之后，计算时间与描述此频率范围所需的正常模式的数量成比例。中型分子的结果表明，计算时间最多减少了1个数量级，而精度损失可忽略不计。