非线性光学原子响应理论及最新进展

New Insights and Applications from Atom Response Theory of Nonlinear Optical Materials

二阶非线性光学晶体材料通过倍频效应转换激光频率,并且调制激光的振幅和位相,在现代制造、激光医疗、光通信,以及基础科学研究领域都有重要用途。本文简要介绍了近年来在部分响应泛函方法的基础上发展起来的非线性光学原子响应理论。该理论使人们能够在第一性原理计算的基础上定量评估单个组成原子及轨道对非线性光学晶体材料倍频效应的贡献。在此基础上,本团队还发展了一套普适的以物理性能为标准的基团划分方案,为确定倍频效应的功能基元提供了概念基础。本工作对该理论方法的最新进展及其带来的一些新观点,如导带的作用、原子负贡献、静态偶极矩的作用、非共价基团的压倒性贡献、线性规律等进行解释和阐述,并给出了在新材料设计中的应用实例。

The second-order nonlinear optical(NLO)crystal materials with the capability of converting the laser frequency,and modulating the amplitude and phase of the laser,are indispensable in practical applications,such as modern manufacturing,laser medical treatment,and communications,as well as in fundamental research.This article provides a brief review of the atom response theory(ART)of nonlinear optical materials developed on the basis of the partial response functional(PRF)method.ART analysis makes it possible to quantitatively evaluate the contribution of individual constituent atoms and orbitals to the second harmonic generation(SHG)response of a nonlinear optical crystal material based on the first principles density functional theory calculations.Besides,a general group division scheme based on physical performance was developed,which provides the conceptual foundation for determining the functional motifs of the SHG effect.In this review,the latest progress of atom response theory and the related new concepts and insights,such as the role of the conduction band,negative atomic contributions,the role of static dipole moment,the overwhelming contribution of non-covalent groups,linear relationships,etc.are explained and elaborated,and some examples for the design of new materials are also given.