An inverse P-Cygni profile of H¹³CO⁺ (1 $\to$ 0) in G31.41+0.31 was recently observed, which indicates the presence of an infalling gas envelope. Also, an outflow tracer, SiO, was observed. Here, exclusive radiative transfer modelings have been implemented to generate synthetic spectra of some key species (H¹³CO⁺, HCN, SiO, NH₃, CH₃CN, CH₃OH, CH₃SH, and CH₃NCO) and extract the physical features to infer the excitation conditions of the surroundings where they observed. The gas envelope is assumed to be accreting in a spherically symmetric system towards the central hot core region. Our principal intention was to reproduce the observed line profiles toward G31.41+0.31 and extract various physical parameters. The LTE calculation with CASSIS and non-LTE analysis with the RATRAN radiative transfer codes are considered for the modeling purpose. The best-fitted line parameters are derived, which represents the prevailing physical condition of the gas envelope. Our results suggest that an infalling gas could explain the observed line profiles of all the species mentioned above except SiO. An additional outflow component is required to confer the SiO line profile. Additionally, an astrochemical model is implemented to explain the observed abundances of various species in this source.

H ¹³ CO ⁺ (1$\to$0) 在 G31.41+0.31 最近被观察到，这表明存在下落的气体包层。此外，还观察到流出示踪剂 SiO。在这里，已经实施了独特的辐射传输模型来生成一些关键物质（H ¹³ CO ⁺、HCN、SiO、NH ₃、CH ₃ CN、CH ₃ OH、CH ₃ SH 和 CH ₃NCO）并提取物理特征以推断他们观察到的周围环境的激发条件。假设气体包层在球对称系统中向中心热核区域吸积。我们的主要目的是重现观测到的 G31.41+0.31 线轮廓并提取各种物理参数。出于建模目的，考虑了使用 CASSIS 的 LTE 计算和使用 RATRAN 辐射传输代码的非 LTE 分析。导出了最适合的线参数，它代表了气体包层的主要物理条件。我们的结果表明，下落的气体可以解释除 SiO 之外的上述所有物种的观察线轮廓。需要额外的流出组件来赋予 SiO 线轮廓。此外，