On the Orthogonality of Orbitals in Subsystem Kohn–Sham Density Functional Theory

Khait, Yuriy G.; Hoffmann, Mark R.

doi:10.1016/b978-0-444-59440-2.00003-x

Cited by 41 publications

(71 citation statements)

References 35 publications

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“…Recently, however, embedding schemes based on optimized effective potential [47][48][49], projection operators [45,[50][51][52][53], and fitted functionals [54,55], are paving the way for the correct description of covalent bonds (high density overlap) by FDE.…”

Section: Subsystem Dft and Td-dftmentioning

confidence: 99%

FDE-vdW: A van der Waals inclusive subsystem density-functional theory

Kevorkyants

Eshuis

Pavanello

2014

The Journal of Chemical Physics

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We present a formally exact van der Waals inclusive electronic structure theory, called FDE-vdW, based on the Frozen Density Embedding formulation of subsystem Density-Functional Theory. In subsystem DFT, the energy functional is composed of subsystem additive and non-additive terms. We show that an appropriate definition of the long-range correlation energy is given by the value of the nonadditive correlation functional. This functional is evaluated using

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Section: Subsystem Dft and Td-dftmentioning

confidence: 99%

FDE-vdW: A van der Waals inclusive subsystem density-functional theory

Kevorkyants

Eshuis

Pavanello

2014

The Journal of Chemical Physics

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“…In ref. 21 and 22, Hoffmann and co-workers argue that SDFT and FDE can only be exact if the additional condition that the…”

Section: Theorymentioning

confidence: 99%

“…Following the analysis in ref. 21 and 22, we proceed by creating an explicitly orthonormalized combined set of subsystem orbitals for subsystems A and B, {f orth…”

Section: Ks-like Orbitals Of Subsystem a And B Fmentioning

confidence: 99%

No need for external orthogonality in subsystem density-functional theory

Unsleber

Neugebauer

Jacob

2016

Phys. Chem. Chem. Phys.

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Recent reports on the necessity of using externally orthogonal orbitals in subsystem density-functional theory (SDFT) [Annu. Rep. Comput. Chem., 8, 2012, 53; J. Phys. Chem. A, 118, 2014, 9182] are re-investigated. We show that in the basis-set limit, supermolecular Kohn-Sham-DFT (KS-DFT) densities can exactly be represented as a sum of subsystem densities, even if the subsystem orbitals are not externally orthogonal. This is illustrated using both an analytical example and in basis-set free numerical calculations for an atomic test case. We further show that even with finite basis sets, SDFT calculations using accurate reconstructed potentials can closely approach the supermolecular KS-DFT density, and that the deviations between SDFT and KS-DFT decrease as the basis-set limit is approached. Our results demonstrate that formally, there is no need to enforce external orthogonality in SDFT, even though this might be a useful strategy when developing projection-based DFT embedding schemes.

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“…This non-additive kinetic energy may be approximated, 27,[53][54][55][56][57][58][59][60][61] numerically calculated, 27,38,62 or eliminated all together through subsystem orbital orthogonalization. [63][64][65][66][67][68][69] The use of subsystem orbital orthogonalization methods for exact DFT embedding was studied by the Manby and Miller groups through the use of a constant shift µ-projection operator. 40,41,[70][71][72] This µ-projection operator demonstrated impressive results and in a later paper, Kallay and co-workers suggested 73 the use of the Huzinaga 74-76 level-shift projection operator as an alternative to the µ-projection operator.…”

Section: Introductionmentioning

confidence: 99%

Robust, Accurate, and Efficient: Quantum Embedding Using the Huzinaga Level-Shift Projection Operator for Complex Systems

Graham

Wen

Chulhai

et al. 2020

J. Chem. Theory Comput.

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Wave function (WF) in density functional theory (DFT) embedding methods provide a framework for performing localized, high accuracy WF calculations on a system, while not incurring the full computational cost of the WF calculation on the full system. In order to effectively partition a system into localized WF and DFT subsystems, we utilize the Huzinaga level-shift projection operator within an absolutely localized basis. In this work, we study the ability of the absolutely localized Huzinaga level-shift projection operator method to study complex WF and DFT partitions, including partitions between multiple covalent bonds, a double bond, and transition metal-ligand bonds. We find that our methodology can accurately describe all of these complex partitions. Additionally, we study the robustness of this method with respect to the 1 arXiv:1911.12449v1 [physics.chem-ph] 27 Nov 2019 WF method, specifically where the embedded systems were described using a multiconfigurational WF method. We found that the method is systematically improvable with respect to both the number of atoms in the WF region and the size of the basis set used, with energy errors less than 1 kcal/mol. Additionally, we calculated the adsorption energy of H 2 to a model of an iron metal organic framework to within 1 kcal/mol compared to CASPT2 calculations performed on the full model while incurring only a small fraction of the full computational cost. This work demonstrates that the absolutely localized Huzinaga level-shift projection operator method is applicable to very complex systems with difficult electronic structures.

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On the Orthogonality of Orbitals in Subsystem Kohn–Sham Density Functional Theory

Cited by 41 publications

References 35 publications

FDE-vdW: A van der Waals inclusive subsystem density-functional theory

FDE-vdW: A van der Waals inclusive subsystem density-functional theory

No need for external orthogonality in subsystem density-functional theory

Robust, Accurate, and Efficient: Quantum Embedding Using the Huzinaga Level-Shift Projection Operator for Complex Systems

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