arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.08549physics.chem-ph
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基于4分量Dirac-Coulomb(-Gaunt)哈密顿量的用于芯激发和芯电离态能量的相对论EOM-CCSD

Relativistic EOM-CCSD for core-excited and core-ionized state energies based on the 4-component Dirac-Coulomb(-Gaunt) Hamiltonian

Loïc Halbert, Marta Lopez Vidal, Avijit Shee, Sonia Coriani, André Severo Pereira Gomes

AI总结:

本文实现了基于4分量相对论哈密顿量的CVS-EOM-CCSD方法以计算芯电离势和激发能,发现X2C分子平均场方法对第五周期及以下元素结果与4分量参考值高度一致,并指出小分量双电子积分对重原子芯结合能有不可忽略的贡献。

摘要:

我们报告了一种针对4分量相对论哈密顿量基于运动方程耦合簇单双激发理论(CVS-EOM-CCSD)的芯价分离方法的实现,用于计算相对论芯电离势和芯激发能。借助该能够利用双群对称性的实现,我们研究了不同CVS-EOM-CCSD变体以及基于精确2分量(X2C)框架的不同哈密顿量的使用,对卤素(CH$_3$I、HX和X$^-$,X = Cl-At)和含氙(Xe、XeF$_2$)物种中不同芯电离和激发态能量的影响。我们的结果表明,基于4分量Dirac-Coulomb平均场计算($^2$DC$^M$)的X2C分子平均场方法[Sikkema等,J. Chem. Phys. 2009, 131, 124116],能够提供与参考4分量能量几乎无法区分的芯激发和电离能,适用范围直至并包括第五周期元素。我们观察到,小分量基组上的双电子积分对碘或砹等原子的K边和L边芯结合能产生不可忽略的贡献,并且基于Dirac-Coulomb-Gaunt平均场计算($^2$DCG$^M$)的方法显著比通过原子平均场积分包含屏蔽双电子自旋-轨道相互作用的X2C计算更准确。

英文摘要:

We report an implementation of the core-valence separation approach to the 4-component relativistic Hamiltonian based equation-of-motion coupled-cluster with singles and doubles theory (CVS-EOM-CCSD), for the calculation of relativistic core-ionization potentials and core-excitation energies. With this implementation, which is capable of exploiting double group symmetry, we investigate the effects of the different CVS-EOM-CCSD variants, and the use of different Hamiltonians based on the exact 2-component (X2C) framework, on the energies of different core ionized and excited states in halogen (CH$_3$I, HX and X$^-$, X = Cl-At) and xenon containing (Xe, XeF$_2$) species. Our results show that the X2C molecular mean-field approach [Sikkema et al., J. Chem. Phys. 2009, 131, 124116], based on 4-component Dirac-Coulomb mean-field calculations ($^2$DC$^M$) is capable of providing core excitations and ionization energies that are nearly indistinguishable from the reference 4-component energies for up to and including fifth-row elements. We observe that two-electron integrals over the small-component basis sets yield non-negligible contributions to core binding energies for the K and L edges for atoms such as iodine or astatine, and that the approach based on Dirac-Coulomb-Gaunt mean-field calculations ($^2$DCG$^M$) are significantly more accurate than X2C calculations for which screened two-electron spin-orbit interactions are included via atomic mean-field integrals.

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