物质材料的结构预测和光物理性能模拟

Structural Predictions and Photophysical Simulations for Materials

具有良好性能的非线性光学材料的成功设计,关键问题在于材料晶体结构和分子结构的可信和有效的预测结果,继而对获得结构信息的材料开展光物理性能计算模拟,这种结构预测与性能模拟结合的方法,为新材料的成功制备创出一条又省时又经济的路子。本文中,我们使用Oganov等发展的全局搜索进化算法的晶体结构预测工具(USPEX软件),成功地预测具有中远红外区透过的二阶非线性光学材料Ba2BiInS5的晶体结构;介绍应用DFT方法优化和预测内嵌富勒烯C2@Sc4@C80-Ih和Sc4C2@C80-Ih分子结构。在结构预测和优化基础上,应用基于态叠加原理(SOS)自行创建的BGP软件与计算激发态性质的软件结合,计算模拟分子晶体、纳米结构分子、生物蛋白分子等体系频率相关和态相关的非线性光学性质(包括不同光学过程的二阶、三阶极化率以及双光子、三光子吸收截面)。此外,还报道了利用固体能带理论与反谐振子模型结合,计算模拟部分离子晶体的二阶和三阶非线性光学性质。

The key question of the successful designs for the nonlinear optical materials with a good performance lies in the credible and effective predictions of material＇s crystal structure and molecular structure.Then,the computational simulations of the photophysical properties will be made based on structural information of materials.In this article,we will describe the applications of a global search evolutionary algorithm coded in USPEX software,which successfully predicted the crystal structures of Ba2BiInS5 with second-order nonlinear optics in far infrared region.At the same time,we will also introduce the optimized structures of embedded fullerenes C2@Sc4@C80-Ih and Sc4C2@C80-Ih based on the DFT method.Based on the predicted and optimized structures of materials,we use the sum-over-states method,coded by ourselves in BGP software,combined with the calculation method of excitation-state properties to simulate the state-related and frequency-dependent nonlinear optical properties of molecular crystals,nano-structured molecules,biological proteins and the other systems.Here,the nonlinear optical properties involve the different optical processes of second-order,third-order polarizabilities and two-photon and three-photon absorption cross-sections.In addition,the calculations of second-order and third-order susceptibilities will be also described for some ionic crystals based on the solid energy band theory combined with anti-harmonic oscillator model.