Hartree-Fock (HF) and Density Functional Theory (DFT) play an important role in computational quantum theory especially in physical chemistry. Melatonin is a hormone produced naturally by the pineal gland that prevents the production of melanin. It is believed to be involved in regulating the reproductive cycle. The energy bandgaps for melatonin structure have been calculated using DFT and HF method at different basis sets. The bond length, bond angle, and dihedral angles for the melatonin compound have been described. The atomic orbital (GIAO), ¹H and ¹³C NMR chemical shifts of the title compound in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d,p) basis set. Using the PCM model, the electronic absorption spectra have been determined using the TD-DFT method based on the B3LYP/6-311G(d,p) level optimized structure in different solvents (DMSO, ethanol, aniline, chloroform, THF, and diethyl ether), the maximum wavelength has been observed in DMSO solvent. Frontier molecular orbitals (FMOs), Molecular electrostatic potential (MEP) surfaces, and thermodynamic parameters have been described for melatonin molecule.

中文翻译：

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褪黑激素的计算和光谱研究

Hartree-Fock (HF) 和密度泛函理论 (DFT) 在计算量子理论中发挥着重要作用，尤其是在物理化学中。褪黑激素是松果体自然产生的一种激素，可防止黑色素的产生。据信它参与调节生殖周期。褪黑激素结构的能带隙已使用 DFT 和 HF 方法在不同的基组下计算。已经描述了褪黑激素化合物的键长、键角和二面角。原子轨道 (GIAO)、¹ H 和¹³使用密度泛函方法 (B3LYP) 和 6-31G(d,p) 基组计算了基态标题化合物的 C NMR 化学位移。使用 PCM 模型，基于 B3LYP/6-311G(d,p) 级优化结构在不同溶剂（DMSO、乙醇、苯胺、氯仿、THF 和二乙基醚），最大波长已在 DMSO 溶剂中观察到。已经描述了褪黑激素分子的前沿分子轨道 (FMO)、分子静电势 (MEP) 表面和热力学参数。