Semilocal and hybrid density embedding calculations of ground-state charge-transfer complexes

Laricchia, Savio; Fabiano, Eduardo; Sala, Fabio Della

doi:10.1063/1.4795825

Cited by 21 publications

(23 citation statements)

References 102 publications

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“…It was shown that choosing single molecular systems as subsystems in subsystem DFT simulations provides the most beneficial error cancelation between the nonadditive kinetic energy and the nonadditive exchange–correlation functionals employed. The error cancelation is particularly important in the computation of radical species, that is, where semilocal exchange–correlation functionals exhibit the largest deviation from reality due to the self‐interaction error …”

Section: Computational Detailsmentioning

confidence: 99%

Charged‐cell periodic DFT simulations via an impurity model based on density embedding: Application to the ionization potential of liquid water

Tölle

Gomes

Ramos

et al. 2018

Int J of Quantum Chemistry

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Calculations of charged systems in periodic boundary conditions (PBC) are problematic because there are spurious interactions between the charges in different periodic images that can affect the physical picture. In addition, the intuitive limit of Coulomb interactions decaying to zero as the interacting charges are placed at infinite separation no longer applies, and for example total energies become undefined. Leveraging subsystem density functional theory (also known as density embedding) we define an impurity model that embeds a finite neutral or charged subsystem within an extended (infinite) surrounding subsystem. The combination of the impurity model and a consistent choice of the Coulomb reference provides us with an algorithm for evaluating the ionization potential (IP) in extended systems. We demonstrate our approach in a pilot calculation of the IP of liquid water, based on a configuration from a prior ab initio molecular dynamics (AIMD) simulation of liquid water (Genova et al., J. Chem. Phys. 2016, 144, 234105). The calculations with the impurity model capture the broadening on the ionization energies introduced by the interactions between the water molecules. Furthermore, the calculated average IP value (10.5 eV) compare favorably to experiments (9.9-10.06 eV) and very recent simulations based on the GW approximation (10.55 eV), while at the same time outperforming density embedding calculations carried out with a naïve handling of the electrostatic interactions (about 7 eV). K E Y W O R D S DFT, embedding, periodic boundary conditions, water 1 | INTRODUCTION Atomistic models of extended systems (such as solids and liquids) typically prescribe the use of periodic boundary conditions (PBC). Once PBC are invoked, one has the choice of evaluating Coulomb interactions in real space or in reciprocal space. If real space is chosen, considering r, r 0 2R 3 then the Coulomb kernel is w r, r 0 ð Þ¼ 1 jr− r 0 j hinting that it decays to zero when two charges are far away. Despite the decay feature of the kernel, Coulomb potentials and energies for extended systems involve conditionally convergent integrals [1] -a complication which is dealt with by switching to reciprocal space. From a purely theoretical standpoint, in PBC, distance is not a well-defined quantity [2] and the physical kernel is only the one represented in reciprocal space, w G ð Þ¼ 4π G j j 2 (G 2 R 3 an element of the reciprocal space). Thus, complications arise because when G = 0, as the Coulomb kernel becomes undefined. In Ewald summations, [3] this is dealt with using a two-prongued approach: the short-range interactions are dealt with in real space (using a cut-off function, typically the error function), and the long-range interactions are dealt with in reciprocal space.In practice, however, the kernel singularity at G = 0 is not problematic because, although w(G) is singular for G = 0, the total charge density ρ(G) is zero for G = 0. We note that neutrality of the charge density in each unit cell is the only physical choice in PBC, beca...

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Section: Computational Detailsmentioning

confidence: 99%

Charged‐cell periodic DFT simulations via an impurity model based on density embedding: Application to the ionization potential of liquid water

Tölle

Gomes

Ramos

et al. 2018

Int J of Quantum Chemistry

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“…In fact, for dipole-dipole and hydrogen bond complexes the TPSS/TPSS-L method is the most accurate, closely followed by the PBE/PBE approach, whereas the PBE0/PBE is not so accurate for these systems [21,22]. On the other hand, PBE0/PBE is very accurate for weakly-interacting and charge-transfer systems [24].…”

Section: Resultsmentioning

confidence: 97%

“…This is due to its promise of achieving potentially exact results at a reduced computational cost, as well as to the high insight into the nature of interacting systems provided by the associated embedding potentials. Thus, numerous applications related to non-covalent [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] as well as covalent bonded systems [28][29][30][31] have been considered. In addition, the frozen density embedding (FDE) method [3,32,33] has emerged as a practical tool for efficient simulations of different properties [18,[33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Subsystem density functional theory with meta-generalized gradient approximation exchange-correlation functionals

Śmiga

Fabiano

Laricchia

et al. 2015

The Journal of Chemical Physics

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We analyze the methodology and the performance of subsystem density functional theory (DFT) with meta-generalized gradient approximation (meta-GGA) exchange-correlation functionals for non-bonded systems. Meta-GGA functionals depend on the Kohn-Sham kinetic energy density (KED), which is not known as an explicit functional of the density. Therefore, they cannot be directly applied in subsystem DFT calculations. We propose a Laplacian-level approximation to the KED which overcomes the problem and provides a simple and accurate way to apply meta-GGA exchange-correlation functionals in subsystem DFT calculations. The so obtained density and energy errors, with respect to the corresponding supermolecular calculations, are comparable with conventional approaches, depending almost exclusively on the approximations in the non-additive kinetic embedding term. An embedding energy error decomposition explains the accuracy of our method.

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“…It has been shown [125][126][127] that employing hybrid XC functionals (i.e. functionals including a fraction of the HF exact exchange) for the evaluation of the intra-fragment XC energy, greatly improves the quality of FDE for chargetransfer complexes, w.r.t.…”

Section: Note On Self-interactionmentioning

confidence: 99%

Subsystem density-functional theory as an effective tool for modeling ground and excited states, their dynamics and many-body interactions

Krishtal

Sinha

Genova

et al. 2015

J. Phys.: Condens. Matter

113

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Subsystem Density-Functional Theory (DFT) is an emerging technique for calculating the electronic structure of complex molecular and condensed phase systems. In this topical review, we focus on some recent advances in this field related to the computation of condensed phase systems, their excited states, and the evaluation of many-body interactions between the subsystems. As subsystem DFT is in principle an exact theory, any advance in this field can have a dual role. One is the possible applicability of a resulting method in practical calculations. The other is the possibility of shedding light on some quantummechanical phenomenon which is more easily treated by subdividing a supersystem into subsystems. An example of the latter is many-body interactions. In the discussion, we present some recent work from our research group as well as some new results, casting them in the current state-of-the-art in this review as comprehensively as possible.2

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Semilocal and hybrid density embedding calculations of ground-state charge-transfer complexes

Cited by 21 publications

References 102 publications

Charged‐cell periodic DFT simulations via an impurity model based on density embedding: Application to the ionization potential of liquid water

Charged‐cell periodic DFT simulations via an impurity model based on density embedding: Application to the ionization potential of liquid water

Subsystem density functional theory with meta-generalized gradient approximation exchange-correlation functionals

Subsystem density-functional theory as an effective tool for modeling ground and excited states, their dynamics and many-body interactions

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