Cosmic evolution is the tale of progressive transition from simplicity to complexity. The newborn universe starts with the simplest atoms formed after the Big Bang and proceeds toward ‘astronomical complex organic molecules’ (astroCOMs). Understanding the chemical evolution of the universe is one of the main aims of Astrochemistry, with the starting point being the knowledge whether a molecule is present in the astronomical environment under consideration and, if so, its abundance. However, the interpretation of astronomical detections and the identification of molecules are not all straightforward. In particular, molecular species characterized by large amplitude motions represent a major challenge for molecular spectroscopy and, in particular, for computational spectroscopy. More in general, for flexible systems, the conformational equilibrium needs to be taken into account and accurately investigated. It is shown that crucial challenges in the computational spectroscopy of astroCOMs can be successfully overcome by combining state‐of‐the‐art quantum‐mechanical approaches with ad hoc treatments of the nuclear motion, thus demonstrating that the rotational and vibrational features can be predicted with the proper accuracy. The second key step in Astrochemistry is understanding how astroCOMs are formed and how they chemically evolve toward more complex species. The challenges in the computational chemistry of astroCOMs are related to the derivation of feasible formation routes in the typically harsh conditions (extremely low temperature and density) of the interstellar medium, as well as the understanding of the chemical evolution of small species toward macromolecules. Within the transition state theory, for instance, it is possible to obtain new astrochemical information by identifying the intermediate species and transition states connecting them in a plausible formation route. Depending on the sophistication of the model, different quantities may be needed. Nevertheless, accuracy can be critical, thus requiring state‐of‐the‐art computational approaches to derive geometries, energies, spectroscopic properties, and thermochemical data for each relevant structure along the reaction path.

中文翻译：

---

天化学的计算挑战

宇宙进化是从简单到复杂的逐步过渡的故事。新生宇宙始于大爆炸之后形成的最简单的原子，并朝着“天文复杂的有机分子”（astroCOMs）前进。了解宇宙的化学演化是天化学的主要目标之一，其起点是了解一个分​​子是否存在于所考虑的天文学环境中，如果存在的话，还应了解其丰度。但是，天文探测的解释和分子的鉴定并非一帆风顺。特别地，以大幅度运动为特征的分子种类代表了分子光谱学，尤其是计算光谱学的主要挑战。一般来说，对于灵活的系统，需要考虑构象平衡并进行精确研究。结果表明，将最先进的量子力学方法与特别指定核运动的处理，从而证明可以正确地预测旋转和振动特征。天体化学的第二个关键步骤是了解astroCOMs是如何形成的，以及它们如何化学演化为更复杂的物种。astroCOM的计算化学方面的挑战与在星际介质的典型苛刻条件（极低的温度和密度）下获得可行的形成途径有关，以及对小分子向大分子化学演化的理解。例如，在过渡态理论中，有可能通过识别中间物种和以合理的形成途径将它们连接起来的过渡态来获得新的地球化学信息。根据模型的复杂程度，可能需要不同数量。然而，精确度至关重要，因此需要最新的计算方法来推导沿着反应路径的每个相关结构的几何形状，能量，光谱性质和热化学数据。