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使用基于从头计算平面波赝势法的CASTEP量化软件计算了铌酸锂(LiNbO3)晶体的电子能带结构和线性光学系数,采用耦合微扰方法(CPHF)计算了铌酸锂晶体的非线性光学系数.折射率和倍频系数的计算结果与实验结果基本符合,计算表明铌酸锂晶体中Nb原子的4d轨道电子态和O原子的2p轨道电子态发生了明显杂化.通过分析铌酸锂晶体的价带顶和导带底电子态密度的组成特点可知这些轨道电子态的杂化是其非线性光学效应的主要来源,同时计算还表明铌酸锂晶体中Li-O键具有明显的共价键性.
The electronic band structure and linear optical coefficient of lithium niobate (LiNbO3) crystal were calculated by CASTEP quantification software based on ab initio calculation of plane wave pseudopotential method. The nonlinear optical coefficient of lithium niobate crystal was calculated by coupled perturbation method (CPHF) The calculated results of refraction index and frequency multiplication coefficient agree well with the experimental results, and the calculations show that the 4d orbital states of Nb atoms and the 2p orbital states of O atoms are obviously hybridized in lithium niobate crystals.Through the analysis of lithium niobate crystals Of the top of the valence band and conduction band bottom electronic density of states of the composition of the characteristics of these orbital electronic states hybrid is the main source of nonlinear optical effects at the same time also shows that lithium niobate crystals Li-O bond with significant covalent Key.