1,2,3-Benzotriazole 4-hydroxybenzoic acid (BTHBA) is synthesized and single crystals of dimension 20 mm × 9 mm × 5 mm are grown from methanol solvent by conventional solution growth method. Single crystal X-ray diffraction data show that BTHBA belongs to the orthorhombic crystallographic system with non-centrosymmetric space group Pna21. The grown organic nonlinear optical (NLO) crystal is subjected to various characterizations like powder X-ray diffraction, UV–vis–NIR, photoconductivity, thermogravimetric differential thermal analysis (TG-DTA), and chemical etching analysis. Optimization of the molecular structure, highest occupied molecular orbital–lowest unoccupied molecular orbital energy, natural bond orbital analysis, molecular geometry, and molecular electrostatic potential are investigated using Gaussian 09w software. The laser damage threshold value of BTHBA crystal is estimated to be 13.4 GW cm⁻² using a Nd:YAG laser. The third-order NLO susceptibility of BTHBA crystal reveals relatively high values of about 8.95 × 10⁻⁹ esu when compared with that of standard potassium dihydrogen phosphate (KDP) (8.3 × 10⁻¹⁴ esu). Hence it can be effectively employed for various optoelectronic and photonic applications.

中文翻译：

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用于三阶非线性光学 (NLO) 应用的 1,2,3-苯并三唑 4-羟基苯甲酸 (BTHBA) 单晶的理论和实验研究

合成了 1,2,3-苯并三唑 4-羟基苯甲酸 (BTHBA)，并通过常规溶液生长方法从甲醇溶剂中生长出尺寸为 20 mm × 9 mm × 5 mm 的单晶。单晶X射线衍射数据表明，BTHBA属于非中心对称空间群Pna21的正交晶系。对生长的有机非线性光学 (NLO) 晶体进行各种表征，如粉末 X 射线衍射、紫外-可见-近红外、光电导、热重差热分析 (TG-DTA) 和化学蚀刻分析。使用 Gaussian 09w 软件研究了分子结构的优化、最高占据分子轨道-最低未占据分子轨道能量、自然键轨道分析、分子几何形状和分子静电势。^-2使用 Nd:YAG 激光器。与标准磷酸二氢钾 (KDP) (8.3 × 10 -14 esu) 相比，^BTHBA晶体的三阶 NLO 磁化率显示出相对较高的值，约为 8.95 × 10 ^{-9 esu。}因此，它可以有效地用于各种光电和光子应用。