大家帮我翻译一段话吧，化学方面的。不长。

Pyrrole and its derivatives is an important chemical raw materials, its also the more theoretical research of concern in recent years. In this paper, density functional B3LYP method, respectively, in the 6-31G (d) and 6-311G (d, p) basis set level of pyrrolidine, 2,3-substituted product of pyrrole, indole, carbazole and pyrrole oligomerization materials for structural optimization, the basis of optimizing the use of HF, B3LYP method at different basis sets using Gaussian software GIAO and CSGT methods, respectively, on its N-bit H of the chemical shifts calculated by the result of different calculation Comparison between experimental data and their comparison.

吡咯及其衍生物是重要的化工原料，对其理论研究近年也愈受关注。本文采用密度泛函B3LYP方法，分别在6-31G(d)和6-311G(d,p)基组水平上对吡咯、吡咯2，3位取代产物、吲哚、咔唑以及吡咯的低聚物进行结构优化，在优化的基础上，使用HF、B3LYP方法，在不同的基组上，使用Gaussian软件中GIAO和CSGT方法分别对其N位H上的化学位移进行计算，通过不同计算结果之间的对比以及它们与实验值的对比，

Analysis of the following issues:
1. B3LYP/6-31G (d) and B3LYP/6-311G (d, p) basis set to opti