高等学校化学学报 ›› 2021, Vol. 42 ›› Issue (7): 2218.doi: 10.7503/cjcu20210119

• 研究论文 • 上一篇    下一篇

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

应富鸣,计辰儒,苏培峰,吴玮   

  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
  • 收稿日期:2021-02-26 出版日期:2021-07-10 发布日期:2021-04-12
  • 基金资助:
    国家自然科学基金(21733008)

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

YING Fuming, JI Chenru, SU Peifeng, WU Wei()   

  1. 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
  • Received:2021-02-26 Online:2021-07-10 Published:2021-04-12
  • Contact: WU Wei E-mail:weiwu@xmu.edu.cn
  • Supported by:
    This paper is supported by the National Natural Science Foundation of China(21733008)

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.

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

Abstract:

A multireference density functional theory method, named λ-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.

Key words: Complete active space self-consistent field(CASSCF), Density functional theory(DFT), Multireference, Electronic correlation

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