基于完全活性空间自洽场的杂化多组态密度泛函方法λ-DFCAS  

λ-DFCAS:A Hybrid Density Functional Complete Active Space Self Consistent Field Method

作　　者：应富鸣 计辰儒 苏培峰 吴玮 YING Fuming;JI Chenru;SU Peifeng;WU Wei(State Key Laboratory of Physical Chemistry of Solid Surfaces,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry,Chemistry and Chemical Engineering College,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学固体表面物理化学国家重点实验室,福建省理论与计算化学重点实验室,化学化工学院,厦门361005

出　　处：《高等学校化学学报》2021年第7期2218-2226,共9页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21733008,21973077)资助.

摘　　要：提出了一种杂化多组态密度泛函新方法——λ-DFCAS.在λ-DFCAS方法中,电子相关能被分为静态和动态相关能.静态相关能由多组态波函数方法完全活性空间自洽场(CASSCF)得到,而动态相关能由密度泛函理论方法描述.两种相关能的杂化比例由一个可调节的参数λ控制.参数λ的取值取决于分子体系的多组态特性,在0~1之间变化,从而使得λ-DFCAS可以应用于各种强相关分子体系.该方法能够以与CASSCF相当的计算代价获得接近完全活性空间二阶微扰(CASPT2)的计算精度,并具备了大小一致性.A multireference density functional theory method,namedλ-DFCAS,is presented in this paper.Based on the strategy used in λ-DFVB method,the λ-DFCAS method divides electronic correlation into two parts:the static correlation is covered by multi-reference wave function method,complete active space self-consistent field(CASSCF),while the dynamic correlation is provided by Kohn-Sham density functional theory(KS-DFT).The parameter λ in λ-DFCAS,controlling the hybrid extent of dynamic and static correlations,varies according to the multireference character of a given molecular system.The λ-DFCAS method provides a multireference density functional theory with size-consistency.Test examples show that the accuracy of λ-DFCAS is close to the complete active space second perturbation theory(CASPT2)method,while its computational cost is roughly the same as CASSCF.

关 键 词：完全活性空间自洽场方法 密度泛函理论 多组态 电子相关 

分 类 号：O641[理学—物理化学]