The study of the Aromatic Infrared Bands (AIBs) in astronomical environments has opened interesting spectroscopic questions on the effect of anharmonicity on the infrared (IR) spectrum of hot polycyclic aromatic hydrocarbons (PAHs) and related species in isolated conditions. The forthcoming James Webb Space Telescope will unveil unprecedented spatial and spectral details in the AIB spectrum; significant advancement is thus necessary now to model the infrared emission of PAHs, their presumed carriers, with enough detail to exploit the information content of the AIBs. This requires including anharmonicity in such models, and to do so systematically for all species included, requiring a difficult compromise between accuracy and efficiency.

We performed a benchmark study to compare the performances of two methods in calculating anharmonic spectra, comparing them to available experimental data. One is a full quantum method, AnharmoniCaOs, relying on an ab initio potential, and the other relies on Molecular Dynamics simulations using a Density Functional based Tight Binding potential. The first one is found to be very accurate and detailed, but it becomes computationally very expensive for increasing temperature; the second is faster and can be used for arbitrarily high temperatures, but is less accurate. Still, its results can be used to model the evolution with temperature of isolated bands.

We propose a new recipe to model anharmonic AIB emission using minimal assumptions on the general behaviour of band positions and widths with temperature, which can be defined by a small number of empirical parameters. Modelling accuracy will depend critically on these empirical parameters, allowing for an incremental improvement in model results, as better estimates become gradually available.

在天文环境中对芳香族红外波段（AIB）的研究提出了一个有趣的光谱学问题，即非谐性对孤立条件下热多环芳烃（PAHs）和相关物种的红外（IR）光谱的影响。即将到来的詹姆斯·韦伯太空望远镜将揭露AIB光谱中空前的空间和光谱细节；因此，现在有必要取得重大进展，以对PAH（其假定的载波）的红外发射进行建模，并具有足够的细节来利用AIB的信息内容。这就要求在这种模型中包括非谐性，并且要对包括的所有物种系统地进行非谐性，这需要在准确性和效率之间做出艰难的折衷。

我们进行了基准研究，比较了两种方法在计算非谐谱中的性能，并将它们与可用的实验数据进行了比较。一种是完全量子方法，即AnharmoniCaOs，它依赖于从头算势，而另一种则是基于使用基于密度泛函的紧密结合势的分子动力学模拟。发现第一个非常准确和详细，但是对于提高温度而言，它在计算上变得非常昂贵。第二个速度更快，可用于任意高温，但准确性较低。尽管如此，其结果仍可用于模拟隔离带温度的演变。

我们提出了一个新的方法，以对带位置和宽度随温度变化的一般行为的最小假设来模拟非谐AIB发射，该假设可以由少量经验参数来定义。建模精度将主要取决于这些经验参数，随着更好的估计逐渐可用，模型效果将得到逐步改善。