Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060 Kraków, Poland.
J Chem Phys. 2013 Sep 21;139(11):114105. doi: 10.1063/1.4819769.
In this paper it is shown that modest calculations combining first principles evaluations of the molecular properties with electrostatic interaction schemes to account for the crystal environment effects are reliable for predicting and interpreting the experimentally measured electric linear and second-order nonlinear optical susceptibilities of molecular crystals within the experimental error bars. This is illustrated by considering two molecular crystals, namely: 2-methyl-4-nitroaniline and 4-(N,N-dimethylamino)-3-acetamidonitrobenzene. Three types of surrounding effects should be accounted for (i) the polarization due to the surrounding molecules, described here by static electric fields originating from their electric dipoles or charge distributions, (ii) the intermolecular interactions, which affect the geometry and particularly the molecular conformation, and (iii) the screening of the external electric field by the constitutive molecules. This study further highlights the role of electron correlation on the linear and nonlinear responses of molecular crystals and the challenge of describing frequency dispersion.
本文表明，将分子性质的第一性原理评估与静电相互作用方案相结合进行适度计算，可用于预测和解释实验测量的分子晶体的电线性和二阶非线性光学灵敏度，其结果在实验误差范围内是可靠的。通过考虑两种分子晶体，即：2-甲基-4-硝基苯胺和 4-（N，N-二甲基氨基）-3-乙酰氨基硝基苯，说明了这一点。应考虑三种类型的周围环境效应：（i）由周围分子引起的极化，这里通过它们的电偶极子或电荷分布产生的静态电场来描述；（ii）分子间相互作用，它影响几何形状，特别是分子构象；（iii）构成分子对外电场的屏蔽。这项研究进一步强调了电子相关对分子晶体线性和非线性响应的作用，以及描述频率色散的挑战。
