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Author Brito, B.G.A.; Candido, L.; Hai, G.-Q.; Peeters, F.M.
Title Quantum effects in a free-standing graphene lattice : path-integral against classical Monte Carlo simulations Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages (up) 195416
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract In order to study quantum effects in a two-dimensional crystal lattice of a free-standing monolayer graphene, we have performed both path-integral Monte Carlo (PIMC) and classical Monte Carlo (MC) simulations for temperatures up to 2000 K. The REBO potential is used for the interatomic interaction. The total energy, interatomic distance, root-mean-square displacement of the atom vibrations, and the free energy of the graphene layer are calculated. The obtained lattice vibrational energy per atom from the classical MC simulation is very close to the energy of a three-dimensional harmonic oscillator 3k(B)T. The PIMC simulation shows that quantum effects due to zero-point vibrations are significant for temperatures T < 1000 K. The quantum contribution to the lattice vibrational energy becomes larger than that of the classical lattice for T < 400 K. The lattice expansion due to the zero-point motion causes an increase of 0.53% in the lattice parameter. A minimum in the lattice parameter appears at T similar or equal to 500 K. Quantum effects on the atomic vibration amplitude of the graphene lattice and its free energy are investigated.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000368095400004 Publication Date 2015-11-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 1550-235x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 22 Open Access
Notes ; This research was supported by the Brazilian agencies FAPESP, FAPEG, and CNPq, the Flemish Science Foundation (FWO-Vl) and the Methusalem Foundation of the Flemish Government. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number UA @ lucian @ c:irua:131144 Serial 4232
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Author Kang, J.; Horzum, S.; Peeters, F.M.
Title Heterostructures of graphene and nitrogenated holey graphene: Moire pattern and Dirac ring Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages (up) 195419
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Nitrogenated holey graphene (NHG) is a recently synthesized two-dimensional material. In this paper the structural and electronic properties of heterostructures of graphene and NHG are investigated using first-principles and tight-binding calculations. Due to the lattice mismatch between NHG and graphene, the formation of a moire pattern is preferred in the graphene/NHG heterostructure, instead of a lattice-coherent structure. In moire-patterned graphene/NHG, the band gap opening at the K point is negligible, and the linear band dispersion of graphene survives. Applying an electric field modifies the coupling strength between the two atomic layers. The Fermi velocity upsilon(F) is reduced as compared to the one of pristine graphene, and its magnitude depends on the twist angle theta between graphene and NHG: For theta = 0 degrees, upsilon(F) is 30% of that of graphene, and it increases rapidly to a value of 80% with increasing theta. The heterostructure exhibits electron-hole asymmetry in upsilon(F), which is large for small theta. In NHG encapsulated between two graphene layers, a “Dirac ring” appears around the K point. Its presence is robust with respect to the relative stacking of the two graphene layers. These findings can be useful for future applications of graphene/NHG heterostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000364998000006 Publication Date 2015-11-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 1550-235x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 33 Open Access
Notes Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number UA @ lucian @ c:irua:130266 Serial 4189
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Author Missault, N.; Vasilopoulos, P.; Vargiamidis, V.; Peeters, F.M.; Van Duppen, B.
Title Spin- and valley-dependent transport through arrays of ferromagnetic silicene junctions Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages (up) 195423
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We study ballistic transport of Dirac fermions in silicene through arrays of barriers, of width d, in the presence of an exchange field M and a tunable potential of height U or depth-U. The spin-and valley-resolved conductances as functions of U or M, exhibit resonances away from the Dirac point (DP) and close to it a pronounced dip that becomes a gap when a critical electric field E-z is applied. This gap widens by increasing the number of barriers and can be used to realize electric field-controlled switching of the current. The spin p(s) and valley p(v) polarizations of the current near the DP increase with Ez or M and can reach 100% for certain of their values. These field ranges widen significantly by increasing the number of barriers. Also, ps and pv oscillate nearly periodically with the separation between barriers or wells and can be inverted by reversing M.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000364998100006 Publication Date 2015-11-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 1550-235x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 54 Open Access
Notes ; This work was supported by the Canadian NSERC Grant No. OGP0121756 (P.V.) and by the Flemish Science Foundation (FWO-Vl) with a Ph.D. research grant (B.V.D.). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number UA @ lucian @ c:irua:130264 Serial 4247
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Author Martens, K.; Jeong, J.W.; Aetukuri, N.; Rettner, C.; Shukla, N.; Freeman, E.; Esfahani, D.N.; Peeters, F.M.; Topuria, T.; Rice, P.M.; Volodin, A.; Douhard, B.; Vandervorst, W.; Samant, M.G.; Datta, S.; Parkin, S.S.P.
Title Field Effect and Strongly Localized Carriers in the Metal-Insulator Transition Material VO(2) Type A1 Journal article
Year 2015 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 115 Issue 115 Pages (up) 196401
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The intrinsic field effect, the change in surface conductance with an applied transverse electric field, of prototypal strongly correlated VO(2) has remained elusive. Here we report its measurement enabled by epitaxial VO(2) and atomic layer deposited high-kappa dielectrics. Oxygen migration, joule heating, and the linked field-induced phase transition are precluded. The field effect can be understood in terms of field-induced carriers with densities up to approximately 5x10(13) cm(-2) which are trongly localized, as shown by their low, thermally activated mobility ( approximately 1x10(-3) cm(2)/V s at 300 K). These carriers show behavior consistent with that of Holstein polarons and strongly impact the (opto)electronics of VO(2).
Address IBM Research-Almaden, San Jose, California 95120, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000364024800013 Publication Date 2015-11-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 28 Open Access
Notes ; The authors acknowledge B. Hughes, K. Roche, L. Gao, C. Lada, J. Van Houdt, M. Heyns, J. P. Locquet, J. Delmotte, L. Krupp, L. Clark, and FWO (K. M.). S. D. and N. S. acknowledge LEAST (Low Energy Systems Technology), one of six SRC STARnet Centers, sponsored by MARCO/DARPA, for financial support. ; Approved Most recent IF: 8.462; 2015 IF: 7.512
Call Number c:irua:129547 Serial 4051
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Author Shylau, A.A.; Badalyan, S.M.; Peeters, F.M.; Jauho, A.P.
Title Electron polarization function and plasmons in metallic armchair graphene nanoribbons Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 205444
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Plasmon excitations in metallic armchair graphene nanoribbons are investigated using the random phase approximation. An exact analytical expression for the polarization function of Dirac fermions is obtained, valid for arbitrary temperature and doping. We find that at finite temperatures, due to the phase space redistribution among inter-band and intra-band electronic transitions in the conduction and valence bands, the full polarization function becomes independent of temperature and position of the chemical potential. It is shown that for a given width of nanoribbon there exists a single plasmon mode whose energy dispersion is determined by the graphene's fine structure constant. In the case of two Coulomb-coupled nanoribbons, this plasmon splits into in-phase and out-of-phase plasmon modes with splitting energy determined by the inter-ribbon spacing.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000355315400007 Publication Date 2015-05-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 13 Open Access
Notes ; The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation (DNRF58). The work at the University of Antwerp was supported by the Flemisch Science Foundation (FWO-Vl) and the Methusalem Foundation of the Flemish Government. S.M.B. gratefully acknowledges hospitality and support from the Department of Physics at the University of Missouri. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126403 Serial 984
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Author Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P.
Title Mixed pairing symmetries and flux-induced spin current in mesoscopic superconducting loops with spin correlations Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 214504
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We numerically investigate the mixed pairing symmetries inmesoscopic superconducting loops in the presence of spin correlations by solving the Bogoliubov-de Gennes equations self-consistently. The spatial variations of the superconducting order parameters and the spontaneous magnetization are determined by the band structure. When the threaded magnetic flux turns on, the charge and spin currents both emerge and depict periodic evolution. In the case of a mesoscopic loop with dominant triplet p(x) +/- ip(y)-wave symmetry, a slight change of the chemical potential may lead to novel flux-dependent evolution patterns of the ground-state energy and the magnetization. The spin-polarized currents show pronounced quantum oscillations with fractional periods due to the appearance of energy jumps in flux, accompanied with a steplike feature of the enhanced spin current. Particularly, at some appropriate flux, the peaks of the zero-energy local density of states clearly indicate the occurrence of the odd-frequency pairing. In the case of a superconducting loop with dominant singlet d(x2-y2)-wave symmetry, the spatial profiles of the zero-energy local density of states and the magnetization show spin-dependent features on different sample diagonals. Moreover, the evolution of the flux-induced spin current always exhibits an hc/e periodicity.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000355647100003 Publication Date 2015-06-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 15 Open Access
Notes ; This work was supported by the National Natural Science Foundation of China under Grants No. 61371020 and No. 61271163, by the Visiting Scholar Program of Shanghai Municipal Education Commission, and by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126433 Serial 2089
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Author Dell'Anna, L.; Perali, A.; Covaci, L.; Neilson, D.
Title Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages (up) 220502
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity v(F) smaller. We demonstrate that with current experimental techniques, the reduction in vF can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000366500100004 Publication Date 2015-12-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 7 Open Access
Notes ; We thank M. Zarenia for useful discussions. L.D. acknowledges financial support from MIUR: FIRB 2012, Grant No. RBFR12NLNA_002, and PRIN, Grant No. 2010LLKJBX. A.P. and D.N. acknowledge financial support from University of Camerino FAR project CESEMN. L.C. acknowledges financial support from Flemish Science Foundation (FWO). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:130211 Serial 4069
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Author Zhao, C.X.; Xu, W.; Li, L.L.; Zhang, C.; Peeters, F.M.
Title Terahertz plasmon-polariton modes in graphene driven by electric field inside a Fabry-Perot cavity Type A1 Journal article
Year 2015 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 117 Issue 117 Pages (up) 223104
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a theoretical study on plasmon-polariton modes in graphene placed inside an optical cavity and driven by a source-to-drain electric field. The electron velocity and electron temperature are determined by solving self-consistently the momentum-and energy-balance equations in which electron interactions with impurities, acoustic-, and optic-phonons are included. Based on many-body self-consistent field theory, we develop a tractable approach to study plasmon-polariton in an electron gas system. We find that when graphene is placed inside a Fabry-Perot cavity, two branches of the plasmon-polariton modes can be observed and these modes are very much optic-or plasmon-like. The frequencies of these modes depend markedly on driving electric field especially at higher resonant frequency regime. Moreover, the plasmon-polariton frequency in graphene is in terahertz (THz) bandwidth and can be tuned by changing the cavity length, gate voltage, and driving electric field. This work is pertinent to the application of graphene-based structures as tunable THz plasmonic devices. (C) 2015 AIP Publishing LLC.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000356176100004 Publication Date 2015-06-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979;1089-7550; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 13 Open Access
Notes ; This work was supported by the Ministry of Science and Technology of China (Grant No. 2011YQ130018), Department of Science and Technology of Yunnan Province, and by the Chinese Academy of Sciences. F.M.P. was a specially appointed Professor for foreign expert at the Chinese Academy of Sciences. ; Approved Most recent IF: 2.068; 2015 IF: 2.183
Call Number c:irua:127076 Serial 3507
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Author Berdiyorov, G.R.; Bahlouli, H.; Peeters, F.M.
Title Theoretical study of electronic transport properties of a graphene-silicene bilayer Type A1 Journal article
Year 2015 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 117 Issue 117 Pages (up) 225101
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable. (C) 2015 AIP Publishing LLC.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000356176100040 Publication Date 2015-06-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979;1089-7550; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 10 Open Access
Notes ; H. B. and F. M. P. acknowledge support from King Fahd University of Petroleum and Minerals, Saudi Arabia, under the RG1329-1 and RG1329-2 DSR Projects. ; Approved Most recent IF: 2.068; 2015 IF: 2.183
Call Number c:irua:127075 Serial 3611
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Author Szaszko-Bogar, V.; Peeters, F.M.; Foeldi, P.
Title Oscillating spin-orbit interaction in two-dimensional superlattices : sharp transmission resonances and time-dependent spin-polarized currents Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 235311
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We consider ballistic transport through a lateral, two-dimensional superlattice with experimentally realizable, sinusoidally oscillating, Rashba-type spin-orbit interaction (SOI). The periodic structure of the rectangular lattice produces a spin-dependent miniband structure for static SOI. Using Floquet theory, transmission peaks are shown to appear in themini-bandgaps as a consequence of the additional, time-dependent SOI. A detailed analysis shows that this effect is due to the generation of harmonics of the driving frequency, via which, e.g., resonances that cannot be excited in the case of static SOI become available. Additionally, the transmitted current shows space-and time-dependent partial spin polarization, in other words, polarization waves propagate through the superlattice.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000355956500003 Publication Date 2015-06-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 10 Open Access
Notes ; This work was partially supported by the European Union and the European Social Fund through Projects No. TAMOP-4.2.2.C-11/1/KONV-2012-0010 and No. TAMOP-4.2.2.A-11/1/KONV-2012-0060, and by the Hungarian Scientific Research Fund (OTKA) under Contracts No. T81364 and No. 116688. The ELI-ALPS Project (GOP-1.1.1-12/B-2012-0001) is supported by the European Union and cofinanced by the European Regional Development Fund. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126432 Serial 2534
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Author Zhao, S.-X.; Zhang, Y.-R.; Gao, F.; Wang, Y.-N.; Bogaerts, A.
Title Bulk plasma fragmentation in a C4F8 inductively coupled plasma : a hybrid modelling study Type A1 Journal article
Year 2015 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 117 Issue 117 Pages (up) 243303
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000357613900009 Publication Date 2015-06-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979;1089-7550; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 11 Open Access
Notes Approved Most recent IF: 2.068; 2015 IF: 2.183
Call Number c:irua:126477 Serial 261
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Author Aierken, Y.; Sahin, H.; Iyikanat, F.; Horzum, S.; Suslu, A.; Chen, B.; Senger, R.T.; Tongay, S.; Peeters, F.M.
Title Portlandite crystal : bulk, bilayer, and monolayer structures Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 245413
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Ca(OH)(2) crystals, well known as portlandite, are grown in layered form, and we found that they can be exfoliated on different substrates. We performed first principles calculations to investigate the structural, electronic, vibrational, and mechanical properties of bulk, bilayer, and monolayer structures of this material. Different from other lamellar structures such as graphite and transition-metal dichalcogenides, intralayer bonding in Ca(OH)(2) is mainly ionic, while the interlayer interaction remains a weak dispersion-type force. Unlike well-known transition-metal dichalcogenides that exhibit an indirect-to-direct band gap crossover when going from bulk to a single layer, Ca(OH)(2) is a direct band gap semiconductor independent of the number layers. The in-plane Young's modulus and the in-plane shear modulus of monolayer Ca(OH)(2) are predicted to be quite low while the in-plane Poisson ratio is larger in comparison to those in the monolayer of ionic crystal BN. We measured the Raman spectrum of bulk Ca(OH)(2) and identified the high-frequency OH stretching mode A(1g) at 3620 cm(-1). In this study, bilayer and monolayer portlandite [Ca(OH)(2)] are predicted to be stable and their characteristics are analyzed in detail. Our results can guide further research on ultrathin hydroxites.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000356135600007 Publication Date 2015-06-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 29 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem foundation of the Flemish government. Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). H.S. is supported by a FWO Pegasus Long Marie Curie Fellowship. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126983 Serial 2675
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Author Richardson, C.L.; Edkins, S.D.; Berdiyorov, G.R.; Chua, C.J.; Griffiths, J.P.; Jones, G.A.C.; Buitelaar, M.R.; Narayan, V.; Sfigakis, F.; Smith, C.G.; Covaci, L.; Connolly, M.R.;
Title Vortex detection and quantum transport in mesoscopic graphene Josephson-junction arrays Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 245418
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We investigate mesoscopic Josephson-junction arrays created by patterning superconducting disks on monolayer graphene, concentrating on the high-T/T-c regime of these devices and the phenomena which contribute to the superconducting glass state in diffusive arrays. We observe features in the magnetoconductance at rational fractions of flux quanta per array unit cell, which we attribute to the formation of flux-quantized vortices. The applied fields at which the features occur are well described by Ginzburg-Landau simulations that take into account the number of unit cells in the array. We find that the mean conductance and universal conductance fluctuations are both enhanced below the critical temperature and field of the superconductor, with greater enhancement away from the graphene Dirac point.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000356129800012 Publication Date 2015-06-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 2 Open Access
Notes ; This work was financially supported by the Engineering and Physical Sciences Research Council, and an NPL/EPSRC Joint Postdoctoral Partnership. Supporting data for this paper is available at the DSpace@Cambridge data repository (https://www.repository.cam.ac.uk/handle/1810/248242). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126982 Serial 3865
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Author Sobrino Fernandez, M.M.; Neek-Amal, M.; Peeters, F.M.
Title AA-stacked bilayer square ice between graphene layers Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages (up) 245428
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Water confined between two graphene layers with a separation of a few A forms a layered two-dimensional ice structure. Using large scale molecular dynamics simulations with the adoptable ReaxFF interatomic potential we found that flat monolayer ice with a rhombic-square structure nucleates between the graphene layers which is nonpolar and nonferroelectric. We provide different energetic considerations and H-bonding results that explain the interlayer and intralayer properties of two-dimensional ice. The controversial AA stacking found experimentally [Algara-Siller et al., Nature (London) 519, 443 (2015)] is consistent with our minimum-energy crystal structure of bilayer ice. Furthermore, we predict that an odd number of layers of ice has the same lattice structure as monolayer ice, while an even number of ice layers exhibits the square ice AA stacking of bilayer ice.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000366731800004 Publication Date 2015-12-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 1550-235x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 40 Open Access
Notes ; This work was supported by the ESF-Eurographene project CONGRAN, and the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:130203 Serial 4127
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Author Grujić, M.M.; Tadic, M.Z.; Peeters, F.M.
Title Chiral properties of topological-state loops Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (up) 245432
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The angular momentum quantization of chiral gapless modes confined to a circularly shaped interface between two different topological phases is investigated. By examining several different setups, we show analytically that the angular momentum of the topological modes exhibits a highly chiral behavior, and can be coupled to spin and/or valley degrees of freedom, reflecting the nature of the interface states. A simple general one-dimensional model, valid for arbitrarily shaped loops, is shown to predict the corresponding energies and the magnetic moments. These loops can be viewed as building blocks for artificial magnets with tunable and highly diverse properties.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000356928200005 Publication Date 2015-06-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 6 Open Access
Notes ; This work was supported by the Ministry of Education, Science and Technological Development (Serbia), and the Fonds Wetenschappelijk Onderzoek (Belgium). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:127039 Serial 357
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Author Scuracchio, P.; Dobry, A.; Costamagna, S.; Peeters, F.M.
Title Tuning the polarized quantum phonon transmission in graphene nanoribbons Type A1 Journal article
Year 2015 Publication Nanotechnology Abbreviated Journal Nanotechnology
Volume 26 Issue 26 Pages (up) 305401
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract We propose systems that allow a tuning of the phonon transmission function T(omega) in graphene nanoribbons by using C-13 isotope barriers, antidot structures, and distinct boundary conditions. Phonon modes are obtained by an interatomic fifth-nearest neighbor force-constant model (5NNFCM) and T(omega) is calculated using the non-equilibrium Green's function formalism. We show that by imposing partial fixed boundary conditions it is possible to restrict contributions of the in-plane phonon modes to T(omega) at low energy. On the contrary, the transmission functions of out-of-plane phonon modes can be diminished by proper antidot or isotope arrangements. In particular, we show that a periodic array of them leads to sharp dips in the transmission function at certain frequencies omega(nu) which can be pre-defined as desired by controlling their relative distance and size. With this, we demonstrated that by adequate engineering it is possible to govern the magnitude of the ballistic transmission functions T(omega) in graphene nanoribbons. We discuss the implications of these results in the design of controlled thermal transport at the nanoscale as well as in the enhancement of thermo-electric features of graphene-based materials.
Address
Corporate Author Thesis
Publisher Place of Publication Bristol Editor
Language Wos 000358675900010 Publication Date 2015-07-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0957-4484;1361-6528; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.44 Times cited 5 Open Access
Notes ; Discussions with C E Repetto, C R Stia and K H Michel are gratefully acknowledged. This work was partially supported by the Flemish Science Foundation (FWO-Vl) and PIP 11220090100392 of CONICET (Argentina). We acknowledge funding from the FWO (Belgium)-MINCyT (Argentina) collaborative research project. ; Approved Most recent IF: 3.44; 2015 IF: 3.821
Call Number c:irua:127186 Serial 3759
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Author Woo, S.Y.; Gauquelin, N.; Nguyen, H.P.T.; Mi, Z.; Botton, G.A.
Title Interplay of strain and indium incorporation in InGaN/GaN dot-in-a-wire nanostructures by scanning transmission electron microscopy Type A1 Journal article
Year 2015 Publication Nanotechnology Abbreviated Journal Nanotechnology
Volume 26 Issue 26 Pages (up) 344002
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The interplay between strain and composition is at the basis of heterostructure design to engineer new properties. The influence of the strain distribution on the incorporation of indium during the formation of multiple InGaN/GaN quantum dots (QDs) in nanowire (NW) heterostructures has been investigated, using the combined techniques of geometric phase analysis of atomic-resolution images and quantitative elemental mapping from core-loss electron energy-loss spectroscopy within scanning transmission electron microscopy. The variation in In-content between successive QDs within individual NWs shows a dependence on the magnitude of compressive strain along the growth direction within the underlying GaN barrier layer, which affects the incorporation of In-atoms to minimize the local effective strain energy. Observations suggest that the interfacial misfit between InGaN/GaN within the embedded QDs is mitigated by strain partitioning into both materials, and results in normal stresses inflicted by the presence of the surrounding GaN shell. These experimental measurements are linked to the local piezoelectric polarization fields for individual QDs, and are discussed in terms of the photoluminescence from an ensemble of NWs.
Address
Corporate Author Thesis
Publisher Place of Publication Bristol Editor
Language Wos 000359079500003 Publication Date 2015-08-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0957-4484 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.44 Times cited 19 Open Access
Notes Approved Most recent IF: 3.44; 2015 IF: 3.821
Call Number UA @ lucian @ c:irua:136278 Serial 4504
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Author Pizzochero, M.; Leenaerts, O.; Partoens, B.; Martinazzo, R.; Peeters, F.M.
Title Hydrogen adsorption on nitrogen and boron doped graphene Type A1 Journal article
Year 2015 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 27 Issue 27 Pages (up) 425502
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Hydrogen adsorption on boron and nitrogen doped graphene is investigated in detail by means of first-principles calculations. A comprehensive study is performed of the structural, electronic, and magnetic properties of chemisorbed hydrogen atoms and atom pairs near the dopant sites. The main effect of the substitutional atoms is charge doping which is found to greatly affect the adsorption process by increasing the binding energy at the sites closest to the substitutional species. It is also found that doping does not induce magnetism despite the odd number of electrons per atom introduced by the foreign species, and that it quenches the paramagnetic response of chemisorbed H atoms on graphene. Overall, the effects are similar for B and N doping, with only minor differences in the adsorption energetics due to different sizes of the dopant atoms and the accompanying lattice distortions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000362573500008 Publication Date 2015-10-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.649 Times cited 20 Open Access
Notes This work was supported by the Flemish Science Foundation (FWO-Vl). MP gratefully acknowledges the Condensed Matter Theory group at Universiteit Antwerpen for the hospitality during his stay. Approved Most recent IF: 2.649; 2015 IF: 2.346
Call Number c:irua:128759 Serial 3971
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Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor : structure, tail states and strain effects Type A1 Journal article
Year 2015 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 48 Issue 48 Pages (up) 435104
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen-metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced variation in the effective mass is found to be negligible (less than 1%).
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000365876300012 Publication Date 2015-09-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.588 Times cited 23 Open Access
Notes Approved Most recent IF: 2.588; 2015 IF: 2.721
Call Number UA @ lucian @ c:irua:130277 Serial 4153
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Author Huijben, M.; Liu, Y.; Boschker, H.; Lauter, V.; Egoavil, R.; Verbeeck, J.; te Velthuis, S.G.E.; Rijnders, G.; Koster, G.
Title Enhanced local magnetization by interface engineering in perovskite-type correlated oxide heterostructures Type A1 Journal article
Year 2015 Publication Advanced Materials Interfaces Abbreviated Journal Adv Mater Interfaces
Volume 2 Issue 2 Pages (up) 1400416
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000349916000001 Publication Date 2015-01-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2196-7350; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.279 Times cited 30 Open Access
Notes Hercules; 246791 COUNTATOMS; 278510 VORTEX; 246102 IFOX; 312483 ESTEEM2; FWO G004413N; esteem2jra3 ECASJO; Approved Most recent IF: 4.279; 2015 IF: NA
Call Number c:irua:125333 c:irua:125333UA @ admin @ c:irua:125333 Serial 1052
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Author Guerrero, A.; Heidari, H.; Ripolles, T.S.; Kovalenko, A.; Pfannmöller, M.; Bals, S.; Kauffmann, L.-D.; Bisquert, J.; Garcia-Belmonte, G.
Title Shelf life degradation of bulk heterojunction solar cells : intrinsic evolution of charge transfer complex Type A1 Journal article
Year 2015 Publication Laser physics review Abbreviated Journal Adv Energy Mater
Volume 5 Issue 5 Pages (up) 1401997
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Achievement of long-term stability of organic photovoltaics is currently one of the major topics for this technology to reach maturity. Most of the techniques used to reveal degradation pathways are destructive and/or do not allow for real-time measurements in operating devices. Here, three different, nondestructive techniques able to provide real-time information, namely, film absorbance, capacitance-voltage (C-V), and impedance spectroscopy (IS), are combined over a period of 1 year using non-accelerated intrinsic degradation conditions. It is discerned between chemical modifications in the active layer, physical processes taking place in the bulk of the blend from those at the active layer/contact interfaces. In particular, it is observed that during the ageing experiment, the main source for device performance degradation is the formation of donor-acceptor charge-transfer complex (P3HT(center dot+)-PCBM center dot-) that acts as an exciton quencher. Generation of these radical species diminishes photocurrent and reduces open-circuit voltage by the creation of electronic defect states. Conclusions extracted from absorption, C-V, and IS measurements will be further supported by a range of other techniques such as atomic force microscopy, X-ray diffraction, and dark-field imaging of scanning transmission electron microscopy on ultrathin cross-sections.
Address
Corporate Author Thesis
Publisher Place of Publication S.l. Editor
Language Wos 000352708600013 Publication Date 2014-12-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1614-6832; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 16.721 Times cited 30 Open Access OpenAccess
Notes 287594 Sunflower; 335078 Colouratom; ECAS_Sara; (ROMEO:yellow; preprint:; postprint:restricted ; pdfversion:cannot); Approved Most recent IF: 16.721; 2015 IF: 16.146
Call Number c:irua:126000 Serial 2994
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Author Barreca, D.; Carraro, G.; Gasparotto, A.; Maccato, C.; Warwick, M.E.A.; Kaunisto, K.; Sada, C.; Turner, S.; Gönüllü, Y.; Ruoko, T.-P.; Borgese, L.; Bontempi, E.; Van Tendeloo, G.; Lemmetyinen, H.; Mathur, S.
Title Fe2O3-TiO2Nano-heterostructure Photoanodes for Highly Efficient Solar Water Oxidation Type A1 Journal article
Year 2015 Publication Advanced Materials Interfaces Abbreviated Journal Adv Mater Interfaces
Volume 2 Issue 2 Pages (up) 1500313
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Harnessing solar energy for the production of clean hydrogen by photo­electrochemical water splitting represents a very attractive, but challenging approach for sustainable energy generation. In this regard, the fabrication of Fe2O3–TiO2 photoanodes is reported, showing attractive performances [≈2.0 mA cm−2 at 1.23 V vs. the reversible hydrogen electrode in 1 M NaOH] under simulated one-sun illumination. This goal, corresponding to a tenfold photoactivity enhancement with respect to bare Fe2O3, is achieved by atomic layer deposition of TiO2 over hematite (α-Fe2O3) nanostructures fabricated by plasma enhanced-chemical vapor deposition and final annealing at 650 °C. The adopted approach enables an intimate Fe2O3–TiO2 coupling, resulting in an electronic interplay at the Fe2O3/TiO2 interface. The reasons for the photocurrent enhancement determined by TiO2 overlayers with increasing thickness are unraveled by a detailed chemico-physical investigation, as well as by the study of photo­generated charge carrier dynamics. Transient absorption spectroscopy shows that the increased photoelectrochemical response of heterostructured photoanodes compared to bare hematite is due to an enhanced separation of photogenerated charge carriers and more favorable hole dynamics for water oxidation. The stable responses obtained even in simulated seawater provides a feasible route in view of the eventual large-scale generation of renewable energy.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000368914700011 Publication Date 2015-09-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2196-7350; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.279 Times cited 56 Open Access
Notes The authors kindly acknowledge the fi nancial support under the FP7 project “SOLAROGENIX” (NMP4-SL-2012-310333), as well as Padova University ex-60% 2012–2014 projects, Grant No. CPDR132937/13 (SOLLEONE), and Regione Lombardia-INSTM ATLANTE projects. S.T. acknowledges the FWO Flanders for a postdoctoral scholarship. Approved Most recent IF: 4.279; 2015 IF: NA
Call Number c:irua:129201 Serial 3957
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Author Conings, B.; Drijkoningen, J.; Gauquelin, N.; Babayigit, A.; D'Haen, J.; D'Olieslaeger, L.; Ethirajan, A.; Verbeeck, J.; Manca, J.; Mosconi, E.; Angelis, F.D.; Boyen, H.G.;
Title Intrinsic thermal instability of methylammonium lead trihalide perovskite Type A1 Journal article
Year 2015 Publication Laser physics review Abbreviated Journal Adv Energy Mater
Volume 5 Issue 5 Pages (up) 1500477
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Organolead halide perovskites currently are the new front-runners as light absorbers in hybrid solar cells, as they combine efficiencies passing already 20% with deposition temperatures below 100 °C and cheap solution-based fabrication routes. Long-term stability remains a major obstacle for application on an industrial scale. Here, it is demonstrated that significant decomposition effects already occur during annealing of a methylammonium lead triiode perovskite at 85 °C even in inert atmosphere thus violating international standards. The observed behavior supports the view of currently used perovskite materials as soft matter systems with low formation energies, thus representing a major bottleneck for their application, especially in countries with high average temperatures. This result can trigger a broader search for new perovskite families with improved thermal stability.
Address
Corporate Author Thesis
Publisher Place of Publication S.l. Editor
Language Wos 000359374900005 Publication Date 2015-06-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1614-6832; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 16.721 Times cited 1691 Open Access
Notes FWO G004413N; GOA Solarpaint Approved Most recent IF: 16.721; 2015 IF: 16.146
Call Number c:irua:127298UA @ admin @ c:irua:127298 Serial 1719
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Author Van Hoey, S.; Nopens, I.; van der Kwast, J.; Seuntjens, P.
Title Dynamic identifiability analysis-based model structure evaluation considering rating curve uncertainty Type A1 Journal article
Year 2015 Publication Journal of hydrologic engineering Abbreviated Journal
Volume 20 Issue 5 Pages (up) 04014072
Keywords A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Abstract When applying hydrological models, different sources of uncertainty are present, and evaluations of model performances should take these into account to assess model outcomes correctly. Furthermore, uncertainty in the discharge observations complicates the model identification, both in terms of model structure and parameterization. In this paper, the authors compare two different lumped model structures (PDM and NAM) considering uncertainty coming from the rating curve. Limits of acceptability for the model simulations were determined based on derived uncertainty bounds of the discharge observations. The authors applied the DYNamic Identifiability Approach (DYNIA) to identify structural failure of both models and to evaluate the configuration of their structures. In general, similar model performances are observed. However, the model structures tend to behave differently in the course of time, as revealed by the DYNIA approach. Based on the analyses performed, the probability based soil storage representation of the PDM model outperforms the NAM structure. The incorporation of the observation error did not prevent the DYNIA analysis to identify potential model structural deficiencies that are limiting the representation of the seasonal variation, primarily indicated by shifting regions of parameter identifiability. As such, the proposed approach is able to indicate where deficiencies are found and model improvement is needed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000353995400002 Publication Date 2014-03-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1084-0699 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:126056 Serial 7829
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