中文摘要：

采用密度泛函理论（DFT）的B3LYP/6-31G＊方法,对4种洛汾碱类化合物的几何构型进行了优化,在此基础上计算分子的电子结构,并结合有限场FF方法研究了二阶非线性光学（NLO）性质.用含时密度泛函理论（TD-DFT）对上述化合物分子进行吸收光谱的研究.研究表明在4,5-二苯基-2-对甲酰苯基咪唑生色团中4,5苯环上引入硝基和3位N原子引入苄基改变分子的共轭平面,使二阶非线性极化率总有效值（βtot）减小,吸收峰总体蓝移.同时还发现,在CH2Cl2溶剂中a和c分子的λmax主要来源于HOMO→LUMO的π→π＊跃迁,b和d分子的λmax主要来源于HOMO→LUMO＋2的π→π＊跃迁.

英文摘要：

The structures of four lophine derivatives have been optimized at DFT/B3LYP//6-31G＂ method. Based on the obtained stable molecular configuration, we calculated electronic structure and adopted the finite field （FF） method to analyze the second-order nonlinear optical （NLO） properties. Time dependent density functional theory （TD-DFT） methods were employed to calculate absorption spectra of these molecules. The results show that planar conjugation has been changed and the total virtual value of second-order polarizability （βtot） reduced by introducing a benzyl in 3-imidazole and a nitro in 4,5-pyridine ring to lophine. The two groups induce blue-shift in the absorption spectra. Also, it is found that the λmax of a and c are mainly from the λmax electronic transition of HOMO → LUMO in CH2Cl2, The λmax of b and d are mainly from the λmax electronic transition of HOMO → LUMO＋2 in CH2Cl2.