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Updated: May 14, 2025

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

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在N电子价值状态二阶扰动理论 (NEVPT2) 中,密度矩阵的近似值. 三,第三部分. 大型活跃空间计算与选定的配置交互参考

Yang Guo¹, Kantharuban Sivalingam², Vijay Gopal Chilkuri³

¹Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao, Shandong 266237, China.

The Journal of chemical physics

|April 11, 2025

概括

对于全等级的N电子价值状态二阶扰动理论 (FR-NEVPT2) 的新算法使得大活性空间的计算成为可能. 这种方法通过避免存储瓶和恢复静态相关性,有效地处理具有强相关性的系统.

科学领域:

量子化学是一个量子化学.
计算化学计算化学
理论化学理论化学

背景情况:

多引用 (MR) 方法在电子结构计算中难以处理大量的活跃空间.
之前的全级N电子价值状态二阶扰动理论 (FR-NEVPT2) 实现受到了第五阶减少密度矩阵 (RDM) 的存储要求的限制.

研究的目的:

开发一种新的FR-NEVPT2算法,能够处理具有大量活跃空间的系统.
为了克服以前FR-NEVPT2方法的存储限制.
评估新算法的强相关系统的性能.

主要方法:

采用近似的完整活性空间 (CAS) 自相一致场 (SCF) 方法,代配置扩展 (ICE) SCF,用于参考波函数.
由Kollmar等人设计的使用过的中间产品. 构建库普曼矩阵并避免RDM存储瓶.
将新的FR-NEVPT2算法应用于具有活跃空间高达CAS ((34,34) 的系统.

主要成果:

新的FR-NEVPT2算法成功地解决了大型活动空间计算.
即使使用截断的ICE-SCF波函数,FR-NEVPT2也能有效地恢复静态相关性.
证明了该方法在高达CAS (34,34) 的系统上的能力.

结论:

开发的FR-NEVPT2算法是研究具有较大的活跃空间的强相关系系统的强大和高效方法.
这一进步显著扩大了MR扰动理论在计算化学中的适用性.

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