用运动方程耦合簇方法在无自旋精确双组分理论中微扰处理自旋轨道耦合。

Perturbative treatment of spin-orbit-coupling within spin-free exact two-component theory using equation-of-motion coupled-cluster methods.

机构信息

Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.

Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology, Ministry of Education, Sichuan University, Chengdu, China.

出版信息

J Chem Phys. 2018 Jan 28;148(4):044108. doi: 10.1063/1.5012041.

DOI:10.1063/1.5012041

PMID:29390840

Abstract

A scheme is reported for the perturbative calculation of spin-orbit coupling (SOC) within the spin-free exact two-component theory in its one-electron variant (SFX2C-1e) in combination with the equation-of-motion coupled-cluster singles and doubles method. Benchmark calculations of the spin-orbit splittings in Π and P radicals show that the accurate inclusion of scalar-relativistic effects using the SFX2C-1e scheme extends the applicability of the perturbative treatment of SOC to molecules that contain heavy elements. The contributions from relaxation of the coupled-cluster amplitudes are shown to be relatively small; significant contributions from correlating the inner-core orbitals are observed in calculations involving third-row and heavier elements. The calculation of term energies for the low-lying electronic states of the PtH radical, which serves to exemplify heavy transition-metal containing systems, further demonstrates the quality that can be achieved with the pragmatic approach presented here.

摘要

报道了一种方案，用于在自旋自由精确双组分理论（SFX2C-1e）的单电子变分形式中，结合运动方程耦合簇单双激发方法，对自旋轨道耦合（SOC）进行微扰计算。Π 和 P 自由基的自旋轨道分裂的基准计算表明，使用 SFX2C-1e 方案准确包含标量相对论效应，将 SOC 的微扰处理的适用性扩展到包含重元素的分子。结果表明，自洽簇振幅弛豫的贡献相对较小；在涉及第三行和更重元素的计算中，观察到内轨道相关的显著贡献。PtH 自由基低电子态的能级计算进一步证明了用这里提出的实用方法可以达到的质量，PtH 自由基用作含有重过渡金属体系的示例。