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See detailFirst-principles study of the dielectric and dynamical properties of orthorhombic CaMnO3
Bhattacharjee, Satadeep; Bousquet, Eric ULg; Ghosez, Philippe ULg

in Journal of Physics : Condensed Matter (2008), 20

The structural, dielectric and dynamical properties of the low temperature antiferromagnetic orthorhombic phase of CaMnO3 have been computed from first principles, using a density functional theory ... [more ▼]

The structural, dielectric and dynamical properties of the low temperature antiferromagnetic orthorhombic phase of CaMnO3 have been computed from first principles, using a density functional theory approach within the local spin density approximation. The theoretical structural parameters are in good agreement with experiment. The full set of zone-center phonons is reported, allowing new assignment of experimental Raman data and providing reference values for the interpretation of future infrared phonon measurements. It is shown that the static dielectric constant is very large and comparable in amplitude to that of isostructural CaTiO3. In contrast to the pseudocubic structure, it is also highly anisotropic. These features are discussed in relationship to the anomalous Born effective charges and the presence of low frequency polar modes. [less ▲]

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See detailFirst-principles study of the dynamical and nonlinear optical properties of urea single crystals
Hermet, Patrick ULg; Ghosez, Philippe ULg

in Physical Chemistry Chemical Physics [=PCCP] (2010), 12

Raman and infrared spectra of urea single crystals have been calculated using the density functional theory. This allowed us to assign the remaining experimental low-frequency phonon modes. Then, we have ... [more ▼]

Raman and infrared spectra of urea single crystals have been calculated using the density functional theory. This allowed us to assign the remaining experimental low-frequency phonon modes. Then, we have determined the sign of the second-harmonic nonlinear optical susceptibility coefficient in urea to be negative, clarifying a long debate in the literature. Finally, we computed for the first time the electro-optic coefficients of urea. We found that the electronic and ionic contributions have a similar order of magnitude and an opposite sign, yielding a smaller value than that expected, and necessitating further experimental clarifications. [less ▲]

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See detailFirst-principles study of the electro-optic effect in ferroelectric oxides
Veithen, M.; Gonze, X.; Ghosez, Philippe ULg

in Physical Review Letters (2004), 93

We first present a method to compute the electro-optic tensor from first principles, explicitly taking into account the electronic, ionic and piezoelectric contributions. We then study the nonlinear optic ... [more ▼]

We first present a method to compute the electro-optic tensor from first principles, explicitly taking into account the electronic, ionic and piezoelectric contributions. We then study the nonlinear optic behavior of three paradigmatic ferroelectric oxides. Our calculations reveal the dominant contribution of the soft mode to the electro-optic coefficients in LiNbO3 and BaTiO3 and its minor role in PbTiO3. We identify the coupling between the electric field and the polar atomic displacements along the B-O chains as the origin of the large electro-optic response in perovskite ABO(3) compounds. [less ▲]

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See detailFirst-principles study of the ferroelectric Aurivillius phase Bi2WO6
Djani-Ait, Hania ULg; Bousquet, Eric ULg; Kellou, Abdelhafid et al

in Physical Review. B, Condensed Matter and Materials Physics (2012), 86

In order to better understand the reconstructive ferroelectric-paraelectric transition of Bi2WO6, which is unusual within the Aurivillius family of compounds, we performed first-principles calculations of ... [more ▼]

In order to better understand the reconstructive ferroelectric-paraelectric transition of Bi2WO6, which is unusual within the Aurivillius family of compounds, we performed first-principles calculations of the dielectric and dynamical properties of two possible high-temperature paraelectric structures—the monoclinic phase of A2/m symmetry observed experimentally and the tetragonal phase of I4/mmm symmetry—common to most Aurivillius-phase components. Both paraelectric structures exhibit various unstable modes, which, after their condensation, bring the system toward more stable structures of lower symmetry. The calculations confirm that, starting from the paraelectric A2/m phase at high temperatures, the system must undergo a reconstructive transition to reach the P21ab ferroelectric ground state. [less ▲]

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See detailFirst-principles study of the lattice dynamical properties of strontium ruthenate
Miao, Naihua ULg; Bristowe, Nicholas ULg; Xu, Bin et al

in Journal of Physics : Condensed Matter (2014), 26

By means of first-principles calculations, various properties of SrRuO3 are investigated, focusing on its lattice dynamical properties. Despite having a Goldschmidt tolerance factor very close to 1, the ... [more ▼]

By means of first-principles calculations, various properties of SrRuO3 are investigated, focusing on its lattice dynamical properties. Despite having a Goldschmidt tolerance factor very close to 1, the phonon dispersion curves of the high-temperature cubic phase of SrRuO3 show strong antiferrodistortive instabilities. The energetics of metastable phases with different tilt patterns are discussed, concluding that the coupling of oxygen rotation modes with anti-polar Sr motion plays a key role in stabilizing the Pnma phase with respect to alternative rotation patterns. Our systematic analysis confirms previous expectations and contributes to rationalizing better why many ABO3 perovskites, including metallic compounds, exhibit an orthorhombic ground state. The zone-center phonon modes of the Pnma phase have been computed, from which we propose partial reassignment of available experimental data. The full dispersion curves have also been obtained, constituting benchmark results for the interpretation of future measurements and providing access to thermodynamical properties. [less ▲]

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See detailFirst-Principles Study of the Mechanism for B4-to-B1 Phase Transformation in AlN
Xu, Bin ULg; Dong, Jianjun; Stokes, Harold et al

Poster (2009, June)

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See detailFirst-Principles Study of Thermal and Elastic Properties of Al2O3
Xu, Bin ULg; Dong, Jianjun

Poster (2007, February)

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See detailFirst-principles study of transport properties in Os and OsSi
Xu, Bin ULg; Verstraete, Matthieu ULg

in Physical Review. B : Condensed Matter (2013), 87

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See detailFirst-principles study of vibrational and noncollinear magnetic properties of the perovskite to postperovskite pressure transition of $NaMnF_3$
Garcia Castro, Andrés Camilo ULg; Romero, A. H.; Bousquet, Eric ULg

in Physical Review. B, Condensed Matter and Materials Physics (2014), 90

We performed a first-principles study of the structural, vibrational, electronic, and magnetic properties of NaMnF3 under applied isotropic pressure. We found that NaMnF3 undergoes a reconstructive phase ... [more ▼]

We performed a first-principles study of the structural, vibrational, electronic, and magnetic properties of NaMnF3 under applied isotropic pressure. We found that NaMnF3 undergoes a reconstructive phase transition at 8 GPa from the Pnma distorted perovskite structure toward the Cmcm postperovskite structure. This is confirmed by a sudden change of the Mn-F-Mn bondings where the crystal goes from corner-shared octahedra in the Pnma phase to edge-shared octahedra in the Cmcm phase. The magnetic ordering also changes from a G-type antiferromagnetic ordering in the Pnma phase to a C-type antiferromagnetic ordering in the Cmcm phase. Interestingly, we found that the high-spin d-orbital filling is kept at the phase transition which has never been observed in the known magnetic postperovskite structures. We also found a highly noncollinear magnetic ordering in the Cmcm postperovskite phase that drives a large ferromagnetic canting of the spins. We discuss the validity of these results with respect to the U and J parameters of the GGA+U exchange-correlation functional used in our study and conclude that large-spin canting is a promising property of the postperovskite fluoride compounds. [less ▲]

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See detailFiscal policy in an ovrelapping generations model with bequest-as-consumption
Michel, Philippe; Pestieau, Pierre ULg

in Journal of Public Economic Theory (2004)

This paper analyzes an overlapping generation (OLG) growth model wherein saving finances second period consumption and bequest-as-consumption. First, it looks at the market equilibrium and at the optimal ... [more ▼]

This paper analyzes an overlapping generation (OLG) growth model wherein saving finances second period consumption and bequest-as-consumption. First, it looks at the market equilibrium and at the optimal solution; then it turns to the issue of decentralizing the optimal solution with various taxes and transfers. Depending on the available instruments, either a first-best or a second-best optimum can be achieved. Throughout the paper, the results are contrasted with those obtained in the standard OLG model without intergenerationel transfers. [less ▲]

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See detailDe fiscale behandeling van grensoverschrijdende dividenduitkerintgen binnen de interne markt: evoluties in de rechtspraak van het Hof van Justitite
Peeters, Bart ULg

in Houben, Robby; Rutten, Stefan (Eds.) Actuele problemen van financieel, vennootschaps- en fiscaal recht (2007)

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See detailFiscale schulden van een onvermogende schuldenaar
Peeters, Bart ULg

in Algemeen Fiscaal Tijdschrift (2005), 11

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See detailFiscalità e povertà. L'esperienza belga
Bourgeois, Marc ULg

in Rivista Non Profit (2005)

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See detailLa fiscalité communale
Bianchet, Bruno ULg; Xhignesse, Guillaume ULg; Bourgeois, Marc ULg et al

Poster (2013, November 26)

La fiscalité constitue un champ d’investigation qui impacte le territoire de multiples manières. Le financement des communes de Wallonie s’appuie sur différentes sources de recettes, dont la fiscalité ... [more ▼]

La fiscalité constitue un champ d’investigation qui impacte le territoire de multiples manières. Le financement des communes de Wallonie s’appuie sur différentes sources de recettes, dont la fiscalité constitue la plus importante. En 2011, elle représentait près de 48% des recettes globales des communes wallonnes. [less ▲]

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See detailFiscalité des subsides et primes. Certificats Kyoto
Richelle, Isabelle ULg

Conference (2009, October)

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See detailLa fiscalité du patrimoine immobilier détenu par un résident belge en France
Docclo, Caroline ULg; Sirot, St.

in Journal de Droit Fiscal (2013)

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See detailFiscalité et Aménagement du Territoire
Bianchet, Bruno ULg; Xhignesse, Guillaume ULg; Farah, Jihad ULg et al

Report (2014)

Cette recherche consiste en une réflexion sur la fiscalité en tant qu'outil d'aménagement du territoire et en tant que moyen de recontrer les défis du développement territorial, dans le contexte wallon ... [more ▼]

Cette recherche consiste en une réflexion sur la fiscalité en tant qu'outil d'aménagement du territoire et en tant que moyen de recontrer les défis du développement territorial, dans le contexte wallon. Elle s'intègre dans le contexte des débats qui entourent la sixième réforme de l'Etat belge. Elle a pour objectif l'établissement d'un cadre utilisable pour l'évaluation de certains effets territoriaux suite à la mise en oeuvre ou à la modification de politiques fiscales. In fine, elle aboutira à des propositions d'adaptation ou de mise au point de nouvelles mesures en vue de rencontrer les défis territoriaux. Afin d'atteindre ces objectifs, elle se concentre également sur la mise en évidence des liens existants entre le système fiscal en place et certains défis territoriaux. Son objet est restreint au logement et à l'aménagement en lien avec le logement. [less ▲]

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See detailFiscalité et avantages matrimoniaux
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de planification patrimoniale, Le couple, Décès (2009)

Detailed reference viewed: 21 (7 ULg)