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Shin, Shik; Suga, S.; Takeuchi, Masaki; Fujisawa, Masami; Kanzaki, Hiroshi; Fujimori, A.; Daimon, Hiroshi; Ueda, Yuki; Koyamada, Koji; Kachi, Sukeji

doi:10.1103/physrevb.41.4993

Cited by 433 publications

(270 citation statements)

References 53 publications

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“…The unoccupied electronic states are mainly localized at the metallic cations, which play the role of the acidic Lewis centers. The calculated width of the valence band is equal to about 0.6 eV [25] and this value is consistent with the experimental values, both from XPS and UPS experiments [23,60]. The width of the energy gap for V 2 O 5 bulk determined by photoemission experiments [61], optical adsorption [62] and optical reflectance [63] is equal to 2.35, 2.30, and 2.38 eV, respectively, which confirms its semiconductor nature.…”

Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 85%

“…The valence band is localized in the energy region between -12.73 and -5.98 eV. Its width is 6.75 eV, which corresponds to the width of the conductivity band obtained experimentally for the crystal [23,60] and is close to value calculated for the (010) surface [25]. The states of the energy lower than -12.5 eV result from terminal OH groups in the cluster model and are therefore model artifacts.…”

Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 75%

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Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

2009

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Vanadium oxides based materials are well known to play an active role as catalysts in many chemical processes of technological importance like for example hydrocarbon oxidation reactions or selective catalytic reduction of NO x in the presence of ammonia. Usually the (010) surface is pointed out as the most important, however one has to underline that other low-indices surfaces are by far less studied. In the present study the electronic structure of V 2 O 5 (001) and (100) surfaces are determined by ab initio DFT methods using gradient-corrected RPBE exchange-correlation functional. Detailed analyses of the electronic structure of each cluster are performed using charge density distributions, Mayer bond orders, electrostatic potential maps, character of frontier orbitals, and density of states (total as well as partial, atom projected). Results of the calculations show that overall negative charge of the surface oxygen sites scales with their coordination independent of the surface orientation. Terminal oxygen O(1) is charged the least negatively while doubly coordinated atoms -O(2) and O e (2) have charge twice as large. This indicates that bridging (for (001) and (100) netplanes) and edging (only for (001) netplane) oxygen sites are more nucleophilic than terminal vanadyl sites, which becomes important in view of the reactivity of the different sites for surface chemical reactions. Vanadium atoms present at these surfaces are positively charged (electrophilic) and may play a role of electron acceptors. The unsaturated surfaces show a strong tendency to surface relaxation that manifest by large relaxation energies.

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Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 85%

Section: The V 2 O 5 (010) Surface Clusterssupporting

confidence: 75%

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

2009

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“…Essentially in V 6 O 13 one expects the lowest conduction band of V 2 O 5 to be partially filled in addition to having oxygen vacancy related states. Such measurements 46 indeed show an additional feature in photoemission related to the V-3d occupied bands with a well defined Fermi edge. The V 2 O 5 like O-2p dominated valence band edge lies indeed about 2.5 eV below the Fermi edge in V 6 O 13 .…”

Section: B Bulk Band Structure and Optical Properties In Qsgwmentioning

confidence: 76%

Quasiparticle self-consistentGWcalculations of the electronic band structure of bulk and monolayerV2O5

2015

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Quasiparticle self-consistent (QS) GW calculations are performed for bulk and monolayer V2O5. The orbital character of the bands and the bulk monolayer difference at the LDA level are discussed first. We find that the QSGW self-energy overestimates the gap by an unusually large amount. The main reason for this is identified to be the lattice polarization effect: the large LO-TO splittings in this polar material enhance the screening and reduce the screened Coulomb interaction affecting the gap. The effect is estimated to reduce the screened Coulomb interaction and hence the self-energy by a factor 0.38 (for bulk) and brings the calculated optical response functions in fairly good agreement with experiment. For monolayer V2O5, we find that the QSGW gap varies as 1/L with L the size of the spacing between the monolayers in a supercell. This results from the long-range nature of the self-energy Σ = iGW and the similar 1/L behavior of the dielectric screening.

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“…While dynamical effects are crucial in the metal, the excitations of the insulator are well described within a static picture : For the insulator we devise an effective one-particle potential that captures the interacting excitation spectrum. Still, the corresponding ground state is far from a Slater determinant, leading us to introduce the concept of a "many-body Peierls" insulator.The MIT of VO 2 has intrigued solid state physicists for decades [2,3,4,5,6,7,8,9,10,11,12,13,14]. A high temperature metallic rutile (R) phase transforms at T c =340 K into an insulating monoclinic structure (M1), in which vanadium atoms pair up to form tilted dimers along the c-axis.…”

mentioning

confidence: 99%

“…The resistivity jumps up by two orders of magnitude, yet no local moments form. Despite extensive efforts, the mechanism of the transition is still under debate [6,7,8,9,10,11,12]. Two scenarios compete : In the Peierls picture the structural aspect (unit-cell doubling) causes the MIT, while in the Mott picture local correlations predominate.…”

mentioning

confidence: 99%

Effective bandstructure in the insulating phase versus strong dynamical correlations in metallicVO2

Tomczak

Aryasetiawan²,

Biermann

2008

Phys. Rev. B

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Using a general analytical continuation scheme for cluster dynamical mean field calculations, we analyze real-frequency self-energies, momentum-resolved spectral functions, and one-particle excitations of the metallic and insulating phases of VO2. While for the former dynamical correlations and lifetime effects prevent a description in terms of quasi-particles, the excitations of the latter allow for an effective band-structure. We construct an orbital-dependent, but static one-particle potential that reproduces the full many-body spectrum. Yet, the ground state is well beyond a static one-particle description. The emerging picture gives a non-trivial answer to the decade-old question of the nature of the insulator, which we characterize as a "many-body Peierls" state.PACS numbers: 71.27.+a, 71.30.+h, 71.15.Ap Describing electronic correlations is a challenge for modern condensed matter physics. While weak correlations slightly modify quasi-particle states, by broadening them with lifetime effects and shifting their energies, strong enough correlations can entirely invalidate the band picture by inducing a Mott insulating state.In a half-filled one-band model, an insulator is realized above a critical ratio of interaction to bandwidth. Though more complex scenarios exist in realistic multi-band cases, a common feature of compounds that undergo a metal-insulator transition (MIT) upon the change of an external parameter, such as temperature or pressure, is that the respective insulator feels stronger correlations than the metal, since it is precisely their enhancement that drives the system insulating.In this paper we discuss a material where this rule of thumb is inverted : We argue that in VO 2 it is the insulator that is less correlated, in the sense that band-like excitations are better defined and have longer lifetimes than in the metal. Albeit, neither phase is well described by standard band-structure techniques. Using an analytical continuation scheme for quantum Monte Carlo solutions to Dynamical Mean Field Theory (DMFT) [1], we discuss quasi-particle lifetimes, k-resolved spectra (for comparison with future angle resolved photoemission experiments) and effective band-structures. While dynamical effects are crucial in the metal, the excitations of the insulator are well described within a static picture : For the insulator we devise an effective one-particle potential that captures the interacting excitation spectrum. Still, the corresponding ground state is far from a Slater determinant, leading us to introduce the concept of a "many-body Peierls" insulator.The MIT of VO 2 has intrigued solid state physicists for decades [2,3,4,5,6,7,8,9,10,11,12,13,14]. A high temperature metallic rutile (R) phase transforms at T c =340 K into an insulating monoclinic structure (M1), in which vanadium atoms pair up to form tilted dimers along the c-axis. The resistivity jumps up by two orders of magnitude, yet no local moments form. Despite extensive efforts, the mechanism of the transition is still under debate [6,7...

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Vacuum-ultraviolet reflectance and photoemission study of the metal-insulator phase transitions inVO2,V6

Cited by 433 publications

References 53 publications

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

Electronic Structure of Unsaturated V2O5(001) and (100) Surfaces: Ab Initio Density Functional Theory Studies

Quasiparticle self-consistentGWcalculations of the electronic band structure of bulk and monolayerV2O5

Effective bandstructure in the insulating phase versus strong dynamical correlations in metallicVO2

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