使用CNDO/S型近似方法计算NaNO2晶体的倍频系数

本文使用CNDO/S型近似方法,计算(NO₂)^-1的单电子分子轨道,然后按基团理论的通用计算程序计算NaNO₂晶体的倍频系数,计算值和实验值符合得较好,计算结果明确指出:NaNO₂晶体倍频系数各向异性的原因来自基团的共轭π轨道,另外,本文的计算表明,有可能对非线性光学新材料探索提供计算机的预测。本文还就非线性光学效应的双能级模型作了讨论,并指出了它的局限性。 关键词：

CALCULATION OF SHG COEFFICIENTS OF NaNO2 CRYSTALS BY USING CNDO/S METHOD

The molecular orbitals of (NO₂)^-1 grouping were calculated by using the all-valence electron semiempirical CNDO/S method. A general computer program for grouping theory of non-linear optical (ffects was then used to calculate the SHG coefficients of NaNO₂. The agreement between the calculated values and the experimental ones was. found to be quite satisfactory without introducing any adjustable parameters. The results show clearly that the anisotropy of SHG coefficients of NaNO₂ crystals is primarily due to the π molecular orbitals of (NO₂)^-1 grouping. The two-level model of SHG effects as well as its limitations have also been discussed in this paper.