Simplified tuning of long-range corrected density functionals for use in symmetry-adapted perturbation theory

Gray, Montgomery; Herbert, John M.

doi:10.1063/5.0059364

Cited by 16 publications

(43 citation statements)

References 83 publications

(159 reference statements)

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“…The induction energy comes from second-order SAPT but warrants additional discussion and is detailed in Section 2.3. Previous basis-set testing of SAPT0 + MBD reveals that polarized triple-ζ basis sets are both necessary and sufficient to obtain converged energetics [38,47]. This is a unique feature of our hybrid approach to SAPT [39], which replaces the very slow basis-set convergence of perturbative dispersion with a model (MBD) that converges quickly, with the density.…”

Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 84%

“…Quantum-mechanical values of E int were computed using SAPT based on Hartree-Fock (HF) wave functions for the monomers and second-order perturbation theory for the intermolecular Coulomb operators, a method that is usually called SAPT0 [39,46,47], and which is closely related to second-order Møller-Plesset perturbation theory (MP2). However, because second-order dispersion is far from quantitative [38,39,48], we replace it in these calculations with a many-body dispersion (MBD) model [39,49,50], in what we have termed a "hybrid" or "extended" form of SAPT [39].…”

Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 99%

“…This method will be designated as SAPT0 + MBD. At this level of theory, results for small-molecule data sets suggests that errors in E int are within ∼ 1 kcal/mol of the best-available benchmarks [47,50], provided that adequate basis sets are employed [47]. All electronic structure calculations were performed using the Q-Chem software, v. 5.4 [51].…”

Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 99%

“…Unless otherwise specified, all of the SAPT0 calculations reported herein use HF wave functions for the monomers. However, we will report a few SAPT0(KS) calculations [39,47] in which Kohn-Sham (KS) molecular orbitals from density functional theory (DFT) are used in place of HF orbitals. These SAPT0(KS) calculations employ the long-range corrected (LRC) density functional LRC-ωPBE [53].…”

Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 99%

“…These SAPT0(KS) calculations employ the long-range corrected (LRC) density functional LRC-ωPBE [53]. Previous work has emphasized the importance of using an asymptotically correct exchange potential in SAPT calculations [47,48,54,55], and this condition can be achieved in practice via monomer-specific tuning of the rangeseparation parameter (ω) in LRC-ωPBE functional. Although "optimal tuning" of LRC functionals [56,57] is sometimes accomplished using the ionization energy (IE) theorem of DFT, IE = −ε HOMO ,…”

Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 99%

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Interaction Energy Analysis of Monovalent Inorganic Anions in Bulk Water Versus Air/Water Interface

Herbert

Paul

2021

Preprint

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Soft anions exhibit surface activity at the air/water interface that can be probed using surface-sensitive vibrational spectroscopy, yet the statistical mechanics behind this surface activity remains a matter of debate. Here, we examine the nature of anion–water interactions at the air/water interface using a combination of molecular dynamics simulations and quantum-mechanical energy decomposition analysis based on symmetry-adapted perturbation theory. Results are presented for a set of monovalent anions including Cl–, Br–, I–, CN–, OCN–, SCN–, NO2–, NO3–, and ClOn– (n = 1, 2, 3, 4), several of which are archetypal examples of surface-active species. In all cases, we find that average anion–water interaction energies are systematically larger in bulk water although the difference (with respect to the interaction energy in the interfacial environment) is well within the magnitude of the instantaneous fluctuations. Specifically for the surface-active species Br–(aq), I–(aq), ClO4–(aq), and SCN–(aq), and also for ClO–(aq), the charge-transfer (CT) energy is found to be larger at the interface than it is in bulk water, by an amount that is greater than the standard deviation of the fluctuations. The Cl– ion also has a slightly larger CT energy at the interface but NO3–(aq) does not; these two species are borderline cases where consensus is lacking regarding their surface activity. However, CT stabilization amounts to < 20% of the total induction energy, for all of the ions considered here, and CT-free polarization energies are systematically larger in bulk water, again in all cases, so the role of these effects in soft anion surface activity remains unclear. This analysis complements our recent work suggesting that the short-range solvation structure around these ions is scarcely different at the air/water interface from what it is in bulk water. Together, these observations suggest that changes in first-shell hydration structure around soft anions cannot explain observed surface activities.

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Section: Symmetry-adapted Perturbation Theorymentioning

confidence: 84%