Density functional theory for modelling large molecular adsorbate–surface interactions: a mini-review and worked example

Janet, Jon Paul; Zhao, Qing; Ioannidis, Efthymios Ioannis; Kulik, Heather J.

doi:10.1080/08927022.2016.1258465

Cited by 42 publications

(53 citation statements)

References 168 publications

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“…The delocalization error in a semi-local (e.g., generalized gradient approximation, GGA) functional stabilizes overly-delocalized, covalent states 25 and generally gives rise to poor energetics 13 , such as favoring more bonded interactions in low-spin (LS) than in high-spin (HS) states 24,[26][27][28] . Strategies that aim to recover the derivative discontinuity 29 lacking from GGA functionals 5,[30][31][32][33][34][35] include tuned hybrids 25, [36][37][38][39][40][41][42][43][44][45] , DFT+U 26,[46][47][48] , and self-interaction corrections [49][50][51] .…”

Section: Introductionmentioning

confidence: 99%

Unifying Exchange Sensitivity in Transition-Metal Spin-State Ordering and Catalysis through Bond Valence Metrics

Gani

Kulik

2017

J. Chem. Theory Comput.

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Accurate predictions of spin-state ordering, reaction energetics, and barrier heights are critical for the computational discovery of open-shell transition-metal (TM) catalysts. Semilocal approximations in density functional theory, such as the generalized gradient approximation (GGA), suffer from delocalization error that causes them to overstabilize strongly bonded states. Descriptions of energetics and bonding are often improved by introducing a fraction of exact exchange (e.g., erroneous low-spin GGA ground states are instead correctly predicted as high-spin with a hybrid functional). The degree of spin-splitting sensitivity to exchange can be understood based on the chemical composition of the complex, but the effect of exchange on reaction energetics within a single spin state is less well-established. Across a number of model iron complexes, we observe strong exchange sensitivities of reaction barriers and energies that are of the same magnitude as those for spin splitting energies. We rationalize trends in both reaction and spin energetics by introducing a measure of delocalization, the bond valence of the metal-ligand bonds in each complex. The bond valence thus represents a simple-to-compute property that unifies understanding of exchange sensitivity for catalytic properties and spin-state ordering in TM complexes. Close agreement of the resulting per-metal-organic-bond sensitivity estimates, together with failure of alternative descriptors demonstrates the utility of the bond valence as a robust descriptor of how differences in metal-ligand delocalization produce differing relative energetics with exchange tuning. Our unified description explains the overall effect of exact exchange tuning on the paradigmatic two-state FeO/CH reaction that combines challenges of spin-state and reactivity predictions. This new descriptor-sensitivity relationship provides a path to quantifying how predictions in transition-metal complex screening are sensitive to the method used.

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Section: Introductionmentioning

confidence: 99%

Unifying Exchange Sensitivity in Transition-Metal Spin-State Ordering and Catalysis through Bond Valence Metrics

Gani

Kulik

2017

J. Chem. Theory Comput.

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“…These mechanisms are also affected by surface site specificity during adsorption. An effect which is more significant in the adsorption of small adsorbates . The geometry of an interface between a surface and a thick film is largely determined by the constraints that result from the preferences of the adsorbates in terms of surface sites, and in terms of their interactions with the other adsorbates ,.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) ‐ Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer.

2018

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Understanding the surface site preference for single adsorbates, the interactions between adsorbates, how these interactions affect surface site specificity in adsorption and perturb the electronic states of surfaces is important for rationalizing the structure of interfaces and the growth of surface products. Herein, using density functional theory (DFT) calculations, we investigated the adsorption of H S, HS and, S onto Cu(110). The surface site specificity observed for single adsorbates can be largely affected by the presence of other adsorbates, especially S that can affect the adsorption of other species even at distances of 13 Å. The large supercell employed with a surface periodicity of (6×6) allowed us to safely use the Helmholtz method for the determination of the dipole of the surface-adsorbate complex at low adsorbate coverages. We found that the surface perturbation induced by S can be explained by the charge transfer model, H S leads to a perturbation of the surface that arises mostly from Pauli exclusion effects, whereas HS shows a mix of charge transfer and Pauli exclusion effects. These effects have a large contribution to the long range adsorbate-adsorbate interactions observed. Further support for the long range adsorbate-adsorbate interactions are the values of the adsorption energies of adsorbate pairs that are larger than the sum of the adsorption energies of the single adsorbates that constitute the pair. This happens even for large distances and thus goes beyond the H-bond contribution for the H-bond capable adsorbate pairs. Exploiting this knowledge we investigated two models for describing the first stages of growth of a layer of S-atoms at the surface: the formation of islands versus the formation of more homogeneous surface distributions of S-atoms. We found that for coverages lower than 0.5 ML the S-atoms prefer to cluster as islands that evolve to stripes along the [1 1‾ 0] direction with increasing coverage. At 0.5 ML a homogeneous distribution of S-atoms becomes more stable than the formation of stripes. For the coverage equivalent to 1 ML, the formation of two half-monolayers of S-atoms that disrupt the Cu-Cu bonds between the first and second layer is more favorable than the formation of 1 ML homogeneous coverage of S-atoms. Here the S-Cu bond distances and geometries are reminiscent of pyrite, covellite, and to some extent chalcocite. The small energy difference of ≈0.1 eV that exists between this structure and the formation of 1 ML suggests that in a real system at finite temperature both structures may coexist leading to a structure with even lower symmetry.

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“…12 Nevertheless, delocalization errors [13][14] and other biases in semi-local exchange approximations [15][16] (e.g., the generalized gradient approximation or GGA) produce systematic biases toward low-spin states [17][18] that prevent prediction of either qualitative (i.e., ground state identity) or quantitative (i.e., energetic splitting between states) spin-state properties. The bias toward low-spin states may be understood [19][20] by recalling the greater delocalization afforded through greater population of bonding orbitals in low-spin states than in high-spin states.…”

Section: Introductionmentioning

confidence: 99%

Ligand-Field-Dependent Behavior of Meta-GGA Exchange in Transition-Metal Complex Spin-State Ordering

2017

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Prediction of spin-state ordering in transition metal complexes is essential for understanding catalytic activity and designing functional materials. Semi-local approximations in density functional theory, such as the generalized-gradient approximation (GGA), suffer from several errors notably including delocalization error that give rise to systematic bias for more covalently bound low-spin electronic states. Incorporation of exact exchange is known to counteract this bias, instead favoring high-spin states, in a manner that has recently been identified to be ligand-field dependent. In this work, we introduce a tuning strategy to identify the effect of incorporating the Laplacian of the density (i.e., a meta-GGA) in exchange on spinstate ordering. We employ a diverse test set of M(II) and M(III) first-row transition metal ions from Ti to Cu as well as octahedral complexes of these ions with ligands of increasing field strength (i.e., H 2 O, NH 3 , and CO). We show that the sensitivity of spin-state ordering to meta-GGA exchange is highly ligand-field dependent, stabilizing high-spin states in strong-field (i.e., CO) cases and stabilizing low-spin states in weak-field (i.e., H 2 O, NH 3 , and isolated ions) cases. This diverging behavior leads to generally improved treatment of isolated ions and strong field complexes over a standard GGA but worsened treatment for the hexa-aqua or hexa-ammine complexes. These observations highlight the sensitivity of functional performance to subtle changes in chemical bonding.2

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Density functional theory for modelling large molecular adsorbate–surface interactions: a mini-review and worked example

Cited by 42 publications

References 168 publications

Unifying Exchange Sensitivity in Transition-Metal Spin-State Ordering and Catalysis through Bond Valence Metrics

Unifying Exchange Sensitivity in Transition-Metal Spin-State Ordering and Catalysis through Bond Valence Metrics

Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) ‐ Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer.

Ligand-Field-Dependent Behavior of Meta-GGA Exchange in Transition-Metal Complex Spin-State Ordering

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