2-(4-Ethoxyphenyl)isoindoline-1,3-dione molecule has been characterized by experimental FT-IR and UV-visible spectroscopic methods. Density fuctional theory calculations of the molecular structure and vibrational spectra have been performed using the B3LYP/6-311++G(d,p) level of theory for the 2-(4-ethoxyphenyl)isoindoline-1,3-dione. The theoretical results are compared with the experimental observations. Using the TD-DFT methodology, the electronic absorption spectra of the investigated molecule have been calculated. The enthalpy, entropy and heat capacity properties based on the vibrational calculations are calculated at different temperatures. Besides, the frontier orbitals, atomic charges, reactivity descriptors, molecular electrostatic potential, interaction energies and nonlinear optical properties are predicted by the density functional theory calculations.

中文翻译：

---

2-(4 ethoxyphenyl) isoindoline-1,3-dione 的分子结构、光谱和 DFT 研究

2-(4-Ethoxyphenyl)isoindoline-1,3-dione 分子已通过实验 FT-IR 和紫外-可见光谱方法表征。使用 B3LYP/6-311++G(d,p) 理论水平对 2-(4-ethoxyphenyl)isoindoline-1,3-dione 进行了分子结构和振动光谱的密度泛函理论计算。将理论结果与实验观察进行比较。使用 TD-DFT 方法，计算了所研究分子的电子吸收光谱。在不同温度下计算基于振动计算的焓、熵和热容量特性。此外，前沿轨道、原子电荷、反应性描述符、分子静电势、