THEORETICAL STUDY OF THE ELECTRONIC STRUCTURE AND SPECTRAL PROPERTIES OF THE 2,5-DIPHENYLOXAZOLE (PPO) MOLECULE USING QUANTUM CHEMICAL METHODS, ТЕОРЕТИЧЕСКОЕ ИССЛЕДОВАНИЕ ЭЛЕКТРОННОЙ СТРУКТУРЫ И СПЕКТРАЛЬНЫХ СВОЙСТВ МОЛЕКУЛЫ 2,5-ДИФЕНИЛОКСАЗОЛА (PPO) С ИСПОЛЬЗОВАНИЕМ КВАНТОВО-ХИМИЧЕСКИХ МЕТОДОВ, 2,5-DIFENILOKSAZOL (PPO) MOLEKULASINING ELEKTRON TUZILISHI VA SPEKTRAL XOSSALARINI KVANT-KIMYOVIY USULLAR YORDAMIDA NAZARIY TADQIQ ETISH

<jats:p>This theoretical study is aimed at investigating the geometric, electronic and spectral properties of the 2,5-diphenyloxazole (PPO) molecule, which is widely used as a primary organic scintillator in high-energy radiation detectors. In this study quantum chemical methods were used, in particular density functional theory (DFT) with the hybrid B3LYP functional and the 3-21+G* basis set. The calculations were performed with the Gaussian 09 software package, as a result of which the optimal geometry of the molecule and the global minimum energy (-704.379679 Hartree or -19167.1473 eV) were determined. The results show that the PPO molecule possesses high stability, which is confirmed by the HOMO-LUMO energy gap of 4.18 eV (or 0.15362 Hartree).</jats:p>