Dr. Joachim Paier
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Dichtefunktionaltheorie-Studien zur Aktivierung von CO2 an Spinell-Oxidoberflächen
Quelle ↗Förderer: DFG Sachbeihilfe Zeitraum: 07/2019 - 12/2021 Projektleitung: Dr. Joachim Paier
SFB 1109/2: Wechselwirkung zwischen Wasser und Metalloxidoberflächen: Computergestützte Studien an Dünnschichtmodellen (TP C 02)
Quelle ↗Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2018 - 12/2018 Projektleitung: Dr. Joachim Paier
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Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
The Journal of Chemical Physics · 2397 Zitationen · DOI
Hybrid Fock exchange/density functional theory functionals have shown to be very successful in describing a wide range of molecular properties. For periodic systems, however, the long-range nature of the Fock exchange interaction and the resultant large computational requirements present a major drawback. This is especially true for metallic systems, which require a dense Brillouin zone sampling. Recently, a new hybrid functional [HSE03, J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 118, 8207 (2003)] that addresses this problem within the context of methods that evaluate the Fock exchange in real space was introduced. We discuss the advantages the HSE03 functional brings to methods that rely on a reciprocal space description of the Fock exchange interaction, e.g., all methods that use plane wave basis sets. Furthermore, we present a detailed comparison of the performance of the HSE03 and PBE0 functionals for a set of archetypical solid state systems by calculating lattice parameters, bulk moduli, heats of formation, and band gaps. The results indicate that the hybrid functionals indeed often improve the description of these properties, but in several cases the results are not yet on par with standard gradient corrected functionals. This concerns in particular metallic systems for which the bandwidth and exchange splitting are seriously overestimated.
Chemical Reviews · 1038 Zitationen · DOI
ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTOxygen Defects and Surface Chemistry of Ceria: Quantum Chemical Studies Compared to ExperimentJoachim Paier, Christopher Penschke, and Joachim Sauer*View Author Information Institut für Chemie, Humboldt Universität, 10099 Berlin, Germany*E-mail: [email protected]Cite this: Chem. Rev. 2013, 113, 6, 3949–3985Publication Date (Web):May 7, 2013Publication History Received14 December 2012Published online7 May 2013Published inissue 12 June 2013https://pubs.acs.org/doi/10.1021/cr3004949https://doi.org/10.1021/cr3004949review-articleACS PublicationsCopyright © 2013 American Chemical SocietyRequest reuse permissionsArticle Views15497Altmetric-Citations856LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Defects,Defects in solids,Energy,Gold,Oxides Get e-Alerts
The Journal of Chemical Physics · 1009 Zitationen · DOI
Present local and semilocal functionals show significant errors, for instance, in the energetics of small molecules and in the description of band gaps. One possible solution to these problems is the introduction of exact exchange and hybrid functionals. A plane-wave-based algorithm was implemented in VASP (Vienna ab-initio simulation package) to allow for the calculation of the exact exchange. To systematically assess the precision of the present implementation, calculations for the 55 molecules of the G2-1 quantum chemical test set were performed applying the PBE and PBE0 functionals. Excellent agreement for both atomization energies and geometries compared with the results obtained by GAUSSIAN 03 calculations using large basis sets (augmented correlation consistent polarized valence quadruple zeta for the geometry optimization and augmented correlation-consistent polarized valence quintuple zeta for the energy calculations) was found. The mean absolute error for atomization energies between VASP and the experiment is 8.6 and 3.7 kcalmol, as calculated with the PBE and PBE0 functionals, respectively. The mean deviations between VASP and GAUSSIAN are 0.46 and 0.49 kcalmol for the PBE and PBE0 functionals, respectively.
Physical Review B · 986 Zitationen · DOI
We assess the performance of recent density functionals for the exchange-correlation energy of a nonmolecular solid, by applying accurate calculations with the GAUSSIAN, BAND, and VASP codes to a test set of 24 solid metals and nonmetals. The functionals tested are the modified Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol GGA), the second-order GGA (SOGGA), and the Armiento-Mattsson 2005 (AM05) GGA. For completeness, we also test more standard functionals: the local density approximation, the original PBE GGA, and the Tao-Perdew-Staroverov-Scuseria meta-GGA. We find that the recent density functionals for solids reach a high accuracy for bulk properties (lattice constant and bulk modulus). For the cohesive energy, PBE is better than PBEsol overall, as expected, but PBEsol is actually better for the alkali metals and alkali halides. For fair comparison of calculated and experimental results, we consider the zero-point phonon and finite-temperature effects ignored by many workers. We show how GAUSSIAN basis sets and inaccurate experimental reference data may affect the rating of the quality of the functionals. The results show that PBEsol and AM05 perform somewhat differently from each other for alkali metal, alkaline-earth metal, and alkali halide crystals (where the maximum value of the reduced density gradient is about 2), but perform very similarly for most of the other solids (where it is often about 1). Our explanation for this is consistent with the importance of exchange-correlation nonlocality in regions of core-valence overlap.
Physical Review B · 725 Zitationen · DOI
First-principles calculations based on hybrid Hartree-Fock density functionals provide a clear picture of the defect energetics and electronic structure in ZnO. Among the donorlike defects, the oxygen vacancy and hydrogen impurity, which are deep and shallow donors, respectively, are likely to form with a substantial concentration in $n$-type ZnO. The zinc interstitial and zinc antisite, which are both shallow donors, are energetically much less favorable. A strong preference for the oxygen vacancy and hydrogen impurity over the acceptorlike zinc vacancy is found under oxygen-poor conditions, suggesting that the oxygen vacancy contributes to nonstoichiometry and that hydrogen acts as a donor, both of which are without significant compensation by the zinc vacancy. The present results show consistency with the relevant experimental observations.
Journal of Physics Condensed Matter · 694 Zitationen · DOI
We present an overview of the description of structural, thermochemical, and electronic properties of extended systems using several well known hybrid Hartree–Fock/density-functional-theory functionals (PBE0, HSE03, and B3LYP). In addition we address a few aspects of the evaluation of the Hartree–Fock exchange interactions in reciprocal space, relevant to all methods that employ a plane wave basis set and periodic boundary conditions.
The Journal of Chemical Physics · 545 Zitationen · DOI
The B3LYP hybrid functional has shown to successfully predict a wide range of molecular properties. For periodic systems, however, the failure to attain the exact homogeneous electron gas limit as well as the semiempirical construction turns out to be a major drawback of the functional. We rigorously assess the B3LYP functional for solids through calculations of lattice parameters, bulk moduli, and thermochemical properties (atomization energies and reaction energies). The theoretical lattice constants overestimate the experimental ones by approximately 1%, and hence behave similarly to the PBE gradient-corrected exchange-correlation functional. B3LYP atomization energies of solids are drastically worse than those of nonempirical hybrid Hartree-Fock/density functionals (HF/DFT) such as PBE0 and HSE03. These large errors can be traced back to the lack of a proper description of "free-electron-like" systems with a significant itinerant character (metals and small gap semiconductors). Similar calculations using the popular semiempirical B3PW91 hybrid functional, which fulfills the uniform electron gas limit, show a clear improvement over B3LYP regarding atomization energies. Finally, theoretical values for heats of formation for both the B3LYP as well as the B3PW91 functionals are presented. These document a most likely fortuitously good agreement with experiment for the B3LYP hybrid functional.
Physical Review B · 439 Zitationen · DOI
First-principles calculations for the potential photovoltaic material ${\text{Cu}}_{2}{\text{ZnSnS}}_{4}$ (CZTS) are presented using density functional theory and the Perdew-Burke-Ernzerhof exchange-correlation functional as well as using the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. The HSE results compare very favorably to experimental data for the lattice constants and the band gap, as demonstrated for CZTS and selected ternary chalcopyrites such as ${\text{CuInS}}_{2}$, ${\text{CuInSe}}_{2}$, ${\text{CuGaS}}_{2}$, and ${\text{CuGaSe}}_{2}$. Furthermore the HSE band structure is validated using ${G}_{0}{W}_{0}$ quasiparticle calculations. The valence band is found to be made up by an antibonding linear combination of $\text{Cu-}3d$ states and $\text{S-}3p$ states, whereas an isolated band made up by $\text{Sn-}5s$ and $\text{S-}3p$ states dominates the conduction band. In the visible wavelength, the optical properties are determined by transitions from the $\text{Cu-}3d/\text{S-}3p$ states into this conduction band. Comparison of the optical spectra calculated in the independent-particle approximation and using time-dependent hybrid functional theory indicates very small excitonic effects. For the structural properties, the kesterite-type structure of $I\overline{4}$ symmetry is predicted to be the most stable one, possibly along with cation disorder within the Cu-Zn layer. The energy differences between structural modifications are well approximated by a simple ionic model.
Erratum: “Screened hybrid density functionals applied to solids” [J. Chem. Phys. 124, 154709 (2006)]
2006The Journal of Chemical Physics · 384 Zitationen · DOI
Physical Review B · 340 Zitationen · DOI
We present density functional theory (DFT) calculations for MnO, ${\mathrm{Mn}}_{3}{\mathrm{O}}_{4}$, $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Mn}}_{2}{\mathrm{O}}_{3}$, and $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Mn}{\mathrm{O}}_{2}$, using different gradient corrected functionals, such as Perdew-Burke-Ernzerhof (PBE), $\mathrm{PBE}+\mathrm{U}$, and the two hybrid density functional Hartree-Fock methods PBE0 and Heyd-Scuseria-Ernzerhof (HSE). We investigate the structural, electronic, magnetic, and thermodynamical properties of the mentioned compounds. Despite the lack of sufficient experimental information allowing for a comprehensive comparison of our results, we find overall that hybrid functionals provide a more consistent picture than standard PBE. Although $\mathrm{PBE}+\mathrm{U}$ is limited due to the uncertainty of choosing the parameter U, it nevertheless provides satisfactory results in terms of magnetic properties and energies of formation. This is in line with results of PBE0 and HSE calculations, but the $\mathrm{PBE}+\mathrm{U}$ approach tends to overestimate the equilibrium volumes, and also it favors a half-metallic state for the more reduced oxides ${\mathrm{Mn}}_{3}{\mathrm{O}}_{4}$, $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Mn}}_{2}{\mathrm{O}}_{3}$, and $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Mn}{\mathrm{O}}_{2}$, rather than an insulating character as derived from the hybrid functional approaches. The comparison of measured valence-band spectra with the HSE density of states offers a further assessment of the capability of hybrid approaches in overcoming the deficiencies of DFT in treating these kinds of materials.
Physical Review B · 337 Zitationen · DOI
We have calculated static and dynamic response properties for several semiconducting and insulating solids using hybrid functionals, which admix a small fraction of nonlocal Fock exchange to an otherwise semilocal density functional. The calculated static and dynamic properties are clearly improved compared to conventional semilocal density functionals; in particular the oscillator strength at low energy excitations is well described.
physica status solidi (b) · 331 Zitationen · DOI
Abstract Density functional theory (DFT) is the most widely used technique in the realm of first‐principles electronic structure methods. Principally, this is because DFT in the Kohn–Sham (KS) formalism offers the appealing combination of relatively high accuracy and relatively low computational cost. Despite their great successes, traditional semilocal functionals fail to describe some important problems in solid state physics and materials science, the most conspicuous example being the notorious band gap problem. More sophisticated functionals providing greater accuracy without sacrificing computational efficiency are therefore needed. The Heyd–Scuseria–Ernzerhof (HSE) screened hybrid density functional [J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 118 , 8207 (2003); J. Heyd and G. E. Scuseria, J. Chem. Phys. 121 , 1187 (2004)] successfully addresses some of the chief problems which plague semilocal functionals by including only the important parts of exact nonlocal Hartree–Fock‐type exchange. This work discusses some of the concepts underlying HSE and provides illustrative examples highlighting the successes of HSE in numerous solid state applications.
The Journal of Chemical Physics · 245 Zitationen · DOI
We show that the AM05 functional [Armiento and Mattsson, Phys. Rev. B 72, 085108 (2005)] has the same excellent performance for solids as the hybrid density functionals tested in Paier et al. [J. Chem. Phys. 124, 154709 (2006); 125, 249901 (2006)]. This confirms the original finding that AM05 performs exceptionally well for solids and surfaces. Hartree-Fock hybrid calculations are typically an order of magnitude slower than local or semilocal density functionals such as AM05, which is of a regular semilocal generalized gradient approximation form. The performance of AM05 is on average found to be superior to selecting the best of local density approximation and PBE for each solid. By comparing data from several different electronic-structure codes, we have determined that the numerical errors in this study are equal to or smaller than the corresponding experimental uncertainties.
The Journal of Chemical Physics · 217 Zitationen · DOI
We present an implementation of the canonical formulation of second-order Møller-Plesset (MP2) perturbation theory within the projector-augmented-wave method under periodic boundary conditions using a plane wave basis set. To demonstrate the accuracy of our approach we show that our result for the atomization energy of a LiH molecule at the Hartree-Fock+MP2 level is in excellent agreement with well converged Gaussian-type-orbital calculations. To establish the feasibility of employing MP2 perturbation theory in its canonical form to systems that are periodic in three dimensions we calculated the cohesive energy of bulk LiH.
The Journal of Chemical Physics · 189 Zitationen · DOI
Multireference configuration interaction with singles and doubles (MR-CISD) calculations have been performed for the optimization of conical intersections and stationary points on the ethylene excited-state energy surfaces using recently developed methods for the computation of analytic gradients and nonadiabatic coupling terms. Basis set dependence and the effect of various choices of reference spaces for the MR-CISD calculations have been investigated. The crossing seam between the S0 and S1 states has been explored in detail. This seam connects all conical intersections presently known for ethylene. Major emphasis has been laid on the hydrogen-migration path. Starting in the V state of twisted-orthogonal ethylene, a barrierless path to ethylidene was found. The feasibility of ethylidene formation will be important for the explanation of the relative yield of cis and trans H2 elimination.
Physical Review B · 179 Zitationen · DOI
The ground state properties of MnO are investigated using the plane wave based projector augmented wave technique and the so-called ''parameter-free'' hybrid functional approach PBE0 for the approximation of the exchange-correlation energy and potential. The insulating, antiferromagnetically ordered and rhombohedrally distorted B1 structure is found to be the most stable phase of MnO, consistent with experiment. The band gap of 4.02 eV, spin magnetic moment of $4.52\phantom{\rule{0.3em}{0ex}}{\ensuremath{\mu}}_{B}$, optimized lattice parameter $a=4.40\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$, rhombohedral distortion angle $\ensuremath{\alpha}={0.88}^{0}$, density of states, and magnetic properties are all in good agreement with experiment. Results obtained from standard methods such as generalized gradient approximation (GGA), $\mathrm{GGA}+\mathrm{U}$ and periodic Hartee-Fock are also reported for comparative purposes. In line with previous studies, our results suggest that the applied hybrid functional method PBE0, which combines 25% of the exact exchange with a generalized-gradient approximation, corrects the deficiency of semilocal density functionals and provides an accurate quantitative description of the structural, electronic, and magnetic properties of MnO without any adjustable parameter.
Journal of the American Chemical Society · 170 Zitationen · DOI
Ceria (CeO<sub>2</sub>) has recently been found to be a promising catalyst in the selective hydrogenation of alkynes to alkenes. This reaction occurs primarily on highly dispersed metal catalysts, but rarely on oxide surfaces. The origin of the outstanding activity and selectivity observed on CeO<sub>2</sub> remains unclear. In this work, we show that one key aspect of the hydrogenation reaction-the interaction of hydrogen with the oxide-depends strongly on the presence of O vacancies within CeO<sub>2</sub>. Through infrared reflection absorption spectroscopy on well-ordered CeO<sub>2</sub>(111) thin films and density functional theory (DFT) calculations, we show that the preferred heterolytic dissociation of molecular hydrogen on CeO<sub>2</sub>(111) requires H<sub>2</sub> pressures in the mbar regime. Hydrogen depth profiling with nuclear reaction analysis indicates that H species stay on the surface of stoichiometric CeO<sub>2</sub>(111) films, whereas H incorporates as a volatile species into the volume of partially reduced CeO<sub>2-x</sub>(111) thin films (x ∼ 1.8-1.9). Complementary DFT calculations demonstrate that oxygen vacancies facilitate H incorporation below the surface and that they are the key to the stabilization of hydridic H species in the volume of reduced ceria.
Angewandte Chemie International Edition · 168 Zitationen · DOI
Density functional calculations yield energy barriers for H abstraction by oxygen radical sites in Li-doped MgO that are much smaller (12±6 kJ mol(-1)) than the barriers inferred from different experimental studies (80-160 kJ mol(-1)). This raises further doubts that the Li(+)O(˙-) site is the active site as postulated by Lunsford. From temperature-programmed oxidative coupling reactions of methane (OCM), we conclude that the same sites are responsible for the activation of CH4 on both Li-doped MgO and pure MgO catalysts. For a MgO catalyst prepared by sol-gel synthesis, the activity proved to be very different in the initial phase of the OCM reaction and in the steady state. This was accompanied by substantial morphological changes and restructuring of the terminations as transmission electron microscopy revealed. Further calculations on cluster models showed that CH4 binds heterolytically on Mg(2+)O(2-) sites at steps and corners, and that the homolytic release of methyl radicals into the gas phase will happen only in the presence of O2.
New Journal of Physics · 165 Zitationen · DOI
The random-phase approximation to the ground state correlation energy (RPA) in combination with exact exchange (EX) has brought the Kohn–Sham (KS) density functional theory one step closer towards a universal, 'general purpose first-principles method'. In an effort to systematically assess the influence of several correlation energy contributions beyond RPA, this paper presents dissociation energies of small molecules and solids, activation energies for hydrogen transfer and non-hydrogen transfer reactions, as well as reaction energies for a number of common test sets. We benchmark EX + RPA and several flavors of energy functionals going beyond it: second-order screened exchange (SOSEX), single-excitation (SE) corrections, renormalized single-excitation (rSE) corrections and their combinations. Both the SE correction and the SOSEX contribution to the correlation energy significantly improve on the notorious tendency of EX + RPA to underbind. Surprisingly, activation energies obtained using EX + RPA based on a KS reference alone are remarkably accurate. RPA + SOSEX + rSE provides an equal level of accuracy for reaction as well as activation energies and overall gives the most balanced performance, because of which it can be applied to a wide range of systems and chemical reactions.
Physical Review Letters · 161 Zitationen · DOI
van der Waals (vdW) energy corrected density-functional theory [Phys. Rev. Lett. 102, 073005 (2009)] is applied to study the cohesive properties of ionic and semiconductor solids (C, Si, Ge, GaAs, NaCl, and MgO). The required polarizability and dispersion coefficients are calculated using the dielectric function obtained from time-dependent density-functional theory. Coefficients for "atoms in the solid" are then calculated from the Hirshfeld partitioning of the electron density. It is shown that the Clausius-Mossotti equation that relates the polarizability and the dielectric function is accurate even for covalently-bonded semiconductors. We find an overall improvement in the cohesive properties of Si, Ge, GaAs, NaCl, and MgO, when vdW interactions are included on top of the Perdew-Burke-Ernzerhof or Heyd-Scuseria-Ernzerhof functionals. The relevance of our findings for other solids is discussed.
Physical Review B · 157 Zitationen · DOI
We present a detailed study of the adsorption of CO on Cu, Rh, and Pt (111) surfaces in top and hollow sites. The study has been performed using the local density approximation, the gradient corrected functional PBE, and the hybrid Hartree-Fock density functionals PBE0 and HSE03 within the framework of generalized Kohn-Sham density functional theory using a plane-wave basis set. As expected, the local density approximation and generalized gradient approximation functionals show a tendency to favor the hollow sites, at variance with experimental findings that give the top site as the most stable adsorption site. The PBE0 and HSE03 functionals reduce this tendency. In fact, they predict the correct adsorption site for Cu and Rh but fail for Pt. However, even in this case, the hybrid functional destabilizes the hollow site by $50\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ compared to the PBE functional. The results of the total energy calculations are presented along with an analysis of the projected density of states.
The Journal of Chemical Physics · 155 Zitationen · DOI
There has been considerable recent interest in density functionals incorporating random phase approximation (RPA) ground-state correlation. By virtue of its full nonlocality, RPA correlation is compatible with exact Hartree-Fock-type exchange and describes van der Waals interactions exceptionally well [B. G. Janesko et al., J. Chem. Phys. 130, 081105 (2009); J. Chem. Phys. 131, 034110 (2009)]. One caveat is that RPA correlation contains one-electron self-interaction error, which leads to disturbingly large correlation energies in the stretched bond situation of, e.g., H(2)(+), He(2)(+), or Ne(2)(+). In the present work, we show that inclusion of second-order screened exchange rectifies the aforementioned failure of RPA correlation. We present a large number of molecular benchmark results obtained using full-range as well as long-range corrected hybrids incorporating second-order screened exchange correlation. This correction has a generally small, and sometimes undesirable, effect on RPA predictions for chemical properties, but appears to be very beneficial for the dissociation of H(2)(+), He(2)(+), and Ne(2)(+).
O<sub>2</sub> Activation on Ceria Catalysts—The Importance of Substrate Crystallographic Orientation
2017Angewandte Chemie International Edition · 137 Zitationen · DOI
An atomic-level understanding of dioxygen activation on metal oxides remains one of the major challenges in heterogeneous catalysis. By performing a thorough surface-science study of all three low-index single-crystal surfaces of ceria, probably the most important redox catalysts, we provide a direct spectroscopic characterization of reactive dioxygen species at defect sites on the reduced ceria (110) and (100) surfaces. Surprisingly, neither of these superoxo and peroxo species was found on ceria (111), the thermodynamically most stable surface of this oxide. Applying density functional theory, we could relate these apparently inconsistent findings to a sub-surface diffusion of O vacancies on (111) substrates, but not on the less-closely packed surfaces. These observations resolve a long standing debate concerning the location of O vacancies on ceria surfaces and the activation of O<sub>2</sub> on ceria powders.
Journal of the American Chemical Society · 99 Zitationen · DOI
Density functional theory is used for periodic models of monomeric vanadia species deposited on the CeO2(111) surface to study dissociative adsorption of methanol and its subsequent dehydrogenation to formaldehyde. Dispersion-corrected PBE+U calculations are performed and compared with HSE and B3LYP results. Dissociative adsorption of methanol at different sites on VO2·CeO2(111) is highly exothermic with adsorption energies of 1.8 to 1.9 eV (HSE+D). Two relevant pathways for desorption of formaldehyde are found with intrinsic barriers for the redox step of 1.0 and 1.4 eV (HSE+D). The calculated desorption temperatures (370 and 495 K) explain the peaks observed in temperature-programmed desorption experiments. Different sites of the supported catalyst system are involved in the two pathways: (i) methanol can chemisorb on the CeO2 surface filling a so-called pseudovacancy and the H atom is transferred to an V-O-Ce interphase bond or (ii) CH3OH may chemisorb at the V-O-Ce interphase bond and form a V-OCH3 species from which H is transferred to the ceria surface, providing evidence for true cooperativity. In both cases, ceria is directly involved in the redox process, as two electrons are accommodated in Ce f states forming two Ce(3+) ions whereas vanadium remains fully oxidized (V(5+)).
The Journal of Physical Chemistry C · 81 Zitationen · DOI
The majority of the theoretical work that attempted to provide atomic level details on the adsorption of water at the Fe3O4(111) surface is based on conventional density functionals, which suffer from shortcomings such as, for example, self-interaction errors. In an effort to overcome these uncertainties in theoretical results, we use density functional theory (DFT) employing the Perdew, Burke, and Ernzerhof generalized-gradient corrected exchange-correlation functional augmented by a Hubbard-type U parameter. We test for robustness of these results by application of the Heyd, Scuseria, Ernzerhof hybrid functional. For the two relevant metal terminations (Feoct2 and Fetet1) having ambient conditions in mind, we determined the minimum energy adsorption structures up to relatively high water coverage, that is, one, two, and three H2O molecules on the p(1 × 1) surface unit cells, respectively. Water adsorbs dissociatively and strongly exothermic on the Feoct2, whereas molecular adsorption occurs on the Fetet1 termination. Using D2O, two IR signals at 2720 and 2695 cm–1 (typical of OD stretching modes) can be observed for a wide range of temperatures and at moderate water vapor pressures. Our calculations reveal that these IR bands originate from a very stable water dimer-like species. However, at lower temperatures the creation of larger aggregations, such as trimers, appears to be thermodynamically favorable.
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