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arXiv 2001.11832physics.chem-phphysics.comp-ph
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基于密度泛函理论的强关联分子系统基组误差修正

A basis-set error correction based on density-functional theory for strongly correlated molecular systems

Emmanuel Giner, Anthony Scemama, Pierre-François Loos, Julien Toulouse

摘要:

本文将最近提出的基于密度泛函理论(DFT)的基组不完全性修正推广到强关联分子体系[E. Giner等人,J. Chem.Phys.149,194301(2018)]。这种基组校正依赖于波函数计算之间的映射,在有限基组和距离分离DFT(RSDFT)通过定义一个有效的非发散相互作用对应的电子-电子库仑相互作用投影在有限基组。这使得使用RSDFT型互补密度泛函来恢复在这个有限基集中缺失的短程相关效应的主要部分。为了研究弱相关和强相关区域,我们考虑了H10、N2、O2和F2分子的势能曲线直到解离极限,并且我们探索了满足两个关键性质的互补泛函的各种近似:自旋多重态简并(即,相对于自旋投影Sz的能量的独立性)和尺寸一致性。具体来说,我们调查的依赖性的功能上不同类型的顶部对密度和自旋极化。这项研究的关键结果是,显式依赖于上对密度允许一个完全消除任何形式的自旋极化的依赖,而不会有任何显着的精度损失。定量,我们表明,基本设置校正达到化学精度的原子化能量与三重zeta质量的基础上,这里研究的大多数系统。此外,目前的基集不完整性校正提供了平滑的势能曲线沿整个范围的核间距。

英文摘要:

We extend to strongly correlated molecular systems the recently introduced basis-set incompleteness correction based on density-functional theory (DFT) [E. Giner et al., J. Chem. Phys. 149, 194301 (2018)]. This basis-set correction relies on a mapping between wave-function calculations in a finite basis set and range-separated DFT (RSDFT) through the definition of an effective non-divergent interaction corresponding to the electron-electron Coulomb interaction projected in the finite basis set. This enables the use of RSDFT-type complementary density functionals to recover the dominant part of the short-range correlation effects missing in this finite basis set. To study both weak and strong correlation regimes we consider the potential energy curves of the H10, N2, O2, and F2 molecules up to the dissociation limit, and we explore various approximations of complementary functionals fulfilling two key properties: spin-multiplet degeneracy (i.e., independence of the energy with respect to the spin projection Sz) and size consistency. Specifically, we investigate the dependence of the functional on different types of on-top pair densities and spin polarizations. The key result of this study is that the explicit dependence on the on-top pair density allows one to completely remove the dependence on any form of spin polarization without any significant loss of accuracy. Quantitatively, we show that the basis-set correction reaches chemical accuracy on atomization energies with triple-zeta quality basis sets for most of the systems studied here. Also, the present basis-set incompleteness correction provides smooth potential energy curves along the whole range of internuclear distances.

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