Simplified Tuning of Long-Range Corrected Density Functionals for Use in Symmetry-Adapted Perturbation Theory

Gray, Montgomery; Herbert, John J.

doi:10.26434/chemrxiv.14751660

Cited by 3 publications

(22 citation statements)

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“…An ancillary result of this work is the demonstration that screened LRC functionals based on “ω GDD tuning” ,, provide an accurate and convenient means to access condensed-phase electronic spectroscopy, eliminating the computational overhead and system size-dependence associated with the widely used optimal tuning procedure based on the IE criterion (eq ). Together, these developments open a path for simulation of aqueous-phase photochemistry by combining ab initio MD with LR-TDDFT by means of projection-based embedding.…”

Section: Discussionmentioning

confidence: 99%

“…Systematic underestimation of CT excitation energies is largely solved in LR-TDDFT by application of long-range corrected (LRC) functionals, − which are often deployed using an “optimal tuning” procedure based on the ionization energy (IE) criterion, IE = −ε HOMO . Application of this criterion, however, exhibits a troubling dependence on system size, ,− and a different approach is pursued here.…”

Section: Theorymentioning

confidence: 99%

“…As an alternative, in the present work, we employ a “global density-dependent” (GDD) tuning procedure, in which a self-consistent DFT calculation is first performed using a functional such as LRC-ωPBE and then the value of ω is set to an optimal value defined by the average distance ⟨ d x 2 ⟩ 1/2 between an electron in the outer regions of a molecule and the exchange hole in the region of valence MOs. Our group has successfully used this procedure in other contexts, ,− as a means to avoid the hassle associated with tuning based on eq and also as a means to mitigate the dependence of ω-tuning on system size …”

Section: Theorymentioning

confidence: 99%

“…Our group has successfully used this procedure in other contexts, 116,126−128 as a means to avoid the hassle associated with tuning based on eq 35 and also as a means to mitigate the dependence of ω-tuning on system size. 116 The quantity C in eq 36 is an empirical parameter and has been optimized for use with LRC-ωPBE in several different basis sets. 110,126 However, we find that the optimal value of C is sensitive to the fraction of SR-HFX that is used in the self- consistent DFT calculation, thus eq 36 was reparameterized for use with α = 0.40 because the corresponding hybrid PBE functional, which we call PBEh (40), has been demonstrated to afford good electronic energy levels for neat liquid water 129 and for e − (aq).…”

Section: Spade Localizationmentioning

confidence: 99%

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Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

Carter-Fenk

Mundy

Herbert

2021

J. Chem. Theory Comput.

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For many types of vertical excitation energies, linear-response time-dependent density functional theory (LR-TDDFT) offers a useful degree of accuracy combined with unrivaled computational efficiency, although charge-transfer excitation energies are often systematically and dramatically underestimated, especially for large systems and those that contain explicit solvent. As a result, low-energy electronic spectra of solution-phase chromophores often contain tens to hundreds of spurious charge-transfer states, making LR-TDDFT needlessly expensive in bulk solution. Intensity borrowing by these spurious states can affect intensities of the valence excitations, altering electronic bandshapes. At higher excitation energies, it is difficult to distinguish spurious charge-transfer states from genuine charge-transfer-to-solvent (CTTS) excitations. In this work, we introduce an automated diabatization that enables fast and effective screening of the CTTS acceptor space in bulk solution. Our procedure introduces ``natural charge-transfer orbitals'' that provide a means to isolate orbitals that are most likely to participate in a CTTS excitation. Projection of these orbitals onto solvent-centered virtual orbitals provides a criterion for defining the most important solvent molecules in a given excitation and be used as an automated subspace selection algorithm for projection-based embedding of a high-level description of the CTTS state in a lower-level description of its environment. We apply this method to an ab initio molecular dynamics trajectory of I -(aq) and report the lowest-energy CTTS band in the absorption spectrum. Our results are in excellent agreement with experiment and only one-third of the water molecules in the I -(H 2 O) 96 simulation cell need to be described with LR-TDDFT in order to obtain excitation energies that are converged to <0.1 eV. The tools introduced herein will improve the accuracy, efficiency, and usability of LR-TDDFT in solution-phase environments.File list (2)download file view on ChemRxiv NCTA.pdf (10.09 MiB) download file view on ChemRxiv NCTA-SI.pdf (3.58 MiB)

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Section: Discussionmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Spade Localizationmentioning

confidence: 99%

See 2 more Smart Citations

Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

Carter-Fenk

Mundy

Herbert

2021

J. Chem. Theory Comput.

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“…197 The optimally-tuned value of µ does exhibit a strong dependence on system size, however. [319][320][321][322] Strategies to mitigate this dependence have been suggested.…”

Section: Description Of Charge Transfermentioning

confidence: 99%

Density Functional Theory for Electronic Excited States

Herbert¹

2022

Preprint

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This chapter provides a basic introduction to excited-state extensions of density functional theory (DFT), including time-dependent (TD-)DFT in both its linear-response and its explicitly time-dependent formulations. As applied to the Kohn-Sham DFT ground state, linear-response theory affords an eigenvaluetype problem for the excitation energies in a basis of singly-excited Slater determinants, and is widely known simply as "TDDFT" despite its frequency-domain formulation. This form of TDDFT is the mostly widely-used quantum-chemical method for excited states, due to a favorable combination of low cost and reasonable accuracy. The chapter surveys the accuracy of linear-response TDDFT, which is generally more sensitive to the details of the exchange-correlation functional as compared to ground-state DFT, and also describes some known systemic problems exhibited by this approach. Some of those problems can be corrected on a case-by-case basis using orbital-optimized, excited-state self-consistent field (SCF) calculations, in what is known as excited-state Kohn-Sham theory or a "∆SCF" procedure, a class of methods that includes restricted open-shell Kohn-Sham theory. Recent successes of these approaches are highlighted, including double excitations and core-level excitations. Finally, explicitly time-dependent (or "real-time") TDDFT involves propagation of the molecular orbitals in time following an external perturbation, according to the Kohn-Sham analogue of the time-dependent Schrödinger equation. The time-dependent approach has been used to model strong-field electron dynamics, and in the weak-field limit it provides a route to broadband spectra based on the time evolution of the dipole moment function. This is useful for describing high-energy excitations (as in x-ray spectroscopy) and in systems where the density of states is high, as demonstrated by a few examples.

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Comprehensive Basis-Set Testing of Extended Symmetry-Adapted Perturbation Theory and Assessment of Mixed-Basis Combinations to Reduce Cost

Gray

Herbert

2021

Preprint

Self Cite

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Hybrid or "extended" symmetry-adapted perturbation theory (XSAPT) replaces traditional SAPT's treatment of dispersion with better-performing alternatives, while at the same time extending two-body (dimer) SAPT to a many-body treatment of polarization using a self-consistent charge-embedding procedure. The present work presents a systematic study of how XSAPT interaction energies and energy components converge with respect to the choice of Gaussian basis set. Although errors can be reduced in a systematic way using correlation-consistent basis sets, similar performance at lower cost is obtained using Karlsruhe basis sets, and we introduce new versions with limited augmentation (diffuse functions) that are even more efficient. Pople-style basis sets, which are even more efficient, often afford good results if a large number of polarization functions are included. The dispersion models used in XSAPT afford much faster basis-set convergence as compared to the perturbative description of dispersion in conventional SAPT, meaning that "compromise" basis sets (such as jun-cc-pVDZ) are no longer required and benchmark-quality results can be obtained using basis sets of triple-zeta quality. The use of diffuse functions proves to be essential, especially for the description of hydrogen bonds. The "delta(Hartree-Fock)" correction that accounts for high-order induction can be performed in double-zeta basis sets without significant loss of accuracy, leading to a mixed-basis approach that offers 4x speedup over the existing (cubic-scaling) XSAPT approach.

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Simplified Tuning of Long-Range Corrected Density Functionals for Use in Symmetry-Adapted Perturbation Theory

Cited by 3 publications

References 5 publications

Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

Density Functional Theory for Electronic Excited States

Comprehensive Basis-Set Testing of Extended Symmetry-Adapted Perturbation Theory and Assessment of Mixed-Basis Combinations to Reduce Cost

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