Electronic Structure and Bonding of the Early 3d-Transition Metal Diatomic Oxides and Their Ions: ScO0,±, TiO0,±, CrO0,±, and MnO0,±†

Miliordos, Evangelos; Mavridis, Aristides

doi:10.1021/jp910218u

Cited by 81 publications

(137 citation statements)

References 135 publications

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“…For the early series ScO-MnO, the MAD for DMC is 34(3) cm −1 which is near the overall MAD for ScO-ZnO. Over this same range, quantum chemistry 58,59 performs significantly better with MAD's of 4-16 cm −1 . For the mid-row FeO-NiO, DMC performs comparatively well with a MAD of 25(4) cm −1 (49(4) cm −1 for TM) for versus 53-84 cm −1 for quantum chemistry [60][61][62] .…”

Section: B Dimer Propertiesmentioning

confidence: 81%

“…For the case of CrO we observed a large deviation of 0.57(7) eV from experiment. Here the quantum chemical calculations 58 generally perform better with absolute deviations of 0.19(7)-0.60(7) eV. By contrast, Cr is one of the best performers for the IP tests, with a MAD across IP1-4 of just 0.09(2) eV.…”

Section: B Dimer Propertiesmentioning

confidence: 90%

“…Note that prior DMC data is not available for the heavier elements (FeO-ZnO). In addition to displaying DMC results from the present (DMC-TM/DMC-OPT) and prior (DMCprev) studies 20,24,57 , Figure 2 contains reference data from high-level quantum chemical calculations [58][59][60][61][62][63][64] , including multi-reference configuration interaction at the level of singles and doubles excitations (denoted MRCI or MRCI+Q with a Davidson-like correction), and restricted/unrestricted coupled cluster with singles, doubles, and perturbative triples (RCCSD(T)/UCCSD(T)). In the discussion below, the deviation from experiment of these three quantum chemical methods is expressed as a range rather than three separate and individually labeled numbers for brevity.…”

Section: B Dimer Propertiesmentioning

confidence: 99%

“…The bond lengths derived from our DMC binding data 58,59 ). For FeO-NiO, somewhat larger errors were observed for the quantum chemical approaches [60][61][62] (0.9-1.7%) while similar accuracy was maintained in DMC (0.3(1)%).…”

Section: B Dimer Propertiesmentioning

confidence: 99%

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Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

2016

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Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high quality pseudopotentials that are both accurate in QMC and compatible with major planewave electronic structure codes. We have generated a set of neon core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentials to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudpotentials. Our QMC pseudopotential results also compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.PACS numbers: 71.15.Dx, 71.15.Nc Transition metal oxides are an essential class of materials for energy applications. These materials find applications as diverse as catalysis, energy storage, and superconductivity. The ability to tailor the electronic functionality of transition metal oxides is clearly bolstered by continuing to develop a detailed theoretical understanding of these materials. Unfortunately it is this same class of materials that presents some of the greatest resistance to detailed theoretical characterization. Part of this challenge directly relates to the more localized electrons occupying the partially filled d states of the transition metal cations, leading to strong electron-electron interactions. Early characterizations of transition metal oxides by band theory incorrectly predicted many of them to be metals 1 . This departure from the expectations of band theory has lead to the widespread acceptance of strong electron correlation in these materials, in essence meaning that the Coulomb repulsion among electrons needs to be taken into account with some care. Continuum quantum Monte Carlo (QMC) methods 2 have the potential to address this need, as they are capable of taking the many body correlations of interacting electrons explicitly into account with few fundamental approximations. Though the application of such methods generally comes at a high computational cost, with the dramatic increase in available computing power seen in recent years these methods are now being brought to bear 3-9 on this challenging class of materials.One of the most prominent approximations involved in the practical application of quantum Monte Carlo techniques is the use of pseudopotentials to remove the high-energy core electrons. The fundamental idea behind pseudopotentials is that they preserve the electronic characteri...

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Section: B Dimer Propertiesmentioning

confidence: 81%

Section: B Dimer Propertiesmentioning

confidence: 90%

Section: B Dimer Propertiesmentioning

confidence: 99%

Section: B Dimer Propertiesmentioning

confidence: 99%

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Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

2016

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“…8 Our D e values range from 96 to 99 kcal/mol at all levels, which gives D 0 = D e + ZPE(OH) -ZPE(VOH + ) = 94 to 97 kcal/mol. In our experience, our methods for the early first-row transition metal oxides usually underestimate the binding energies by a few kcal/mol, 13,24 and thus the value suggested by Ricca and Bauschlicher should be considered very accurate. Taking the error bars into consideration, the experimental values range from 97.3 to 110 kcal/mol (see above).…”

Section: A Linear Speciesmentioning

confidence: 83%

Ground and excited states of vanadium hydroxide isomers and their cations, VOH0,+ and HVO0,+

Miliordos

Harrison

Hunt

2013

The Journal of Chemical Physics

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Employing correlation consistent basis sets of quadruple-zeta quality and applying both multireference configuration interaction and single-reference coupled cluster methodologies, we studied the electronic and geometrical structure of the [V,O,H](0,+) species. The electronic structure of HVO(0,+) is explained by considering a hydrogen atom approaching VO(0,+), while VOH(0,+) molecules are viewed in terms of the interaction of V(+,2+) with OH(-). The potential energy curves for H-VO(0,+) and V(0,+)-OH have been constructed as functions of the distance between the interacting subunits, and the potential energy curves have also been determined as functions of the H-V-O angle. For the stationary points that we have located, we report energies, geometries, harmonic frequencies, and dipole moments. We find that the most stable bent HVO(0,+) structure is lower in energy than any of the linear HVO(0,+) structures. Similarly, the most stable state of bent VOH is lower in energy than the linear structures, but linear VOH(+) is lower in energy than bent VOH(+). The global minimum on the potential energy surface for the neutral species is the X(3)A" state of bent HVO, although the X(5)A" state of bent VOH is less than 5 kcal/mol higher in energy. The global minimum on the potential surface for the cation is the X(4)Σ(-) state of linear VOH(+), with bent VOH(+) and bent HVO(+) both more than 10 kcal/mol higher in energy. For the neutral species, the bent geometries exhibit significantly higher dipole moments than the linear structures.

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Discrepancy Between Experimental and Theoretical Predictions of the Adiabaticity of Ti⁺+CH₃OH

Sweeny

Ard

McDonald

et al. 2017

Chemistry A European J

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The reaction between Ti and methanol (CH OH) is a model system for competition between activation of C-O, C-H, and O-H bonds and of the role of excited electronic pathways in catalytic processes. Herein, we use experimental kinetics, quantum chemical calculations, and statistical modeling to identify the critical features of the reaction's potential energy surface. Experimental kinetics data between 300 and 600 K shows the reaction largely proceeds through C-O bond activation, yielding TiOH and TiO . Products of the O-H activation pathway, TiOCH and TiOCH are minor, whereas C-H bond activation is not observed at thermal energies. Statistical modeling well-reproduces the experimental results and offers insight into the reaction mechanism. Notably, efficient spin-crossing along the C-O activation pathway is required to produce the observed product distribution, in contrast to a previous estimate of inefficient crossing based on calculation of a small spin-orbit coupling constant. This discrepancy highlights a potential limitation of simple models within the Landau-Zener framework, which are commonly used to calculate surface-crossing probabilities in reactive systems.

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Electronic Structure and Bonding of the Early 3d-Transition Metal Diatomic Oxides and Their Ions: ScO^0,±, TiO^0,±, CrO^0,±, and MnO^0,±^†

Cited by 81 publications

References 135 publications

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Ground and excited states of vanadium hydroxide isomers and their cations, VOH0,+ and HVO0,+

Discrepancy Between Experimental and Theoretical Predictions of the Adiabaticity of Ti⁺+CH₃OH

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Electronic Structure and Bonding of the Early 3d-Transition Metal Diatomic Oxides and Their Ions: ScO0,±, TiO0,±, CrO0,±, and MnO0,±†

Cited by 81 publications

References 135 publications

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Ground and excited states of vanadium hydroxide isomers and their cations, VOH0,+ and HVO0,+

Discrepancy Between Experimental and Theoretical Predictions of the Adiabaticity of Ti++CH3OH

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Electronic Structure and Bonding of the Early 3d-Transition Metal Diatomic Oxides and Their Ions: ScO^0,±, TiO^0,±, CrO^0,±, and MnO^0,±^†

Discrepancy Between Experimental and Theoretical Predictions of the Adiabaticity of Ti⁺+CH₃OH