1. Simulation of the refractive index of Ga doped ZnO nanoparticles embedded in PEDOT:PSS using effective medium approximationsMinseo Park, Dewang Song, Fei Tong, Vahid Mirkhani, 2016, izvirni znanstveni članek Najdeno v: ključnih besedah Povzetek najdenega: ...Effective Medium Approximation, Refractive Index, Zinc Oxide... Ključne besede: Effective Medium Approximation, Refractive Index, Zinc Oxide Objavljeno: 16.01.2017; Ogledov: 3394; Prenosov: 0
Polno besedilo (1,50 MB) |
2. Accelerating GW calculations with optimal polarizability basisLuigi Giacomazzi, G Stenuit, Nicola Marzari, Paolo Umari, X Qian, Stefano Baroni, 2011, izvirni znanstveni članek Najdeno v: ključnih besedah Povzetek najdenega: ...GW approximation, silicon nitride, silica, DFT... Ključne besede: GW approximation, silicon nitride, silica, DFT Objavljeno: 16.10.2018; Ogledov: 2200; Prenosov: 0
Polno besedilo (454,08 KB) |
3. CONTRIBUTION TO DEVELOPMENT OF MESHLESS METHODS FOR FREE AND MOVING BOUNDARY PROBLEMSNAZIA TALAT, 2018, doktorska disertacija Najdeno v: ključnih besedah Povzetek najdenega: ..., diffuse approximate
meshless method, Rayleigh-Taylor instability, Boussinesq approximation, variable
density and viscosity, flow focusing, dripping, jetting... Ključne besede: Two-phase flow, free and moving boundaries, computational fluid dynamics, phasefield formulation, 2D problems, axisymmetric problems, diffuse approximate
meshless method, Rayleigh-Taylor instability, Boussinesq approximation, variable
density and viscosity, flow focusing, dripping, jetting Objavljeno: 11.09.2018; Ogledov: 3136; Prenosov: 128 (1 glas)
Polno besedilo (4,24 MB) |
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5. Guaranteed and robust error bounds for nonconforming approximations of elliptic problemsSergey Repin, Satyendra Tomar, 2011, izvirni znanstveni članek Najdeno v: ključnih besedah Povzetek najdenega: ...a posteriori error estimates, nonconforming approximation, Helmholtz decomposition, Trefftz method... Ključne besede: a posteriori error estimates, nonconforming approximation, Helmholtz decomposition, Trefftz method Objavljeno: 13.11.2018; Ogledov: 2076; Prenosov: 0
Polno besedilo (253,92 KB) |
6. OXYGEN-EXCESS RELATED DEFECTS IN SiO2-BASED MATERIALS: COUPLING THEORY AND EXPERIMENTSBlaž Winkler, 2019, doktorska disertacija Opis: This work is primarily focused on application of standard first-principle computational approaches to model oxygen excess related point defects in amorphous silica. Atomic models with their respective electronic and optical properties are explored together with some conversion mechanisms between defect models.
The first chapter overviews extensive literature about the already known properties of oxygen related defects. Second chapter briefly introduces main methods that have been used in this research, in particular Density Functional Theory (DFT) as energy and force engine with short description of minimal energy path (MEP) algorithm used for modeling chemical/migration reactions, GW approximation for charged electronic excitations (band structure) and Bethe-Salpeter Equation (BSE) for neutral excitations (optical absorption and excitonic structure including electron hole interaction). The third chapter is devoted to the presentation of results. Thanks to the calculation of optical properties of peroxy bridge (POL), a correlation has been found between structural disorder, specifically dihedral angle dispersion, and low coupling with light, which has been identified as main reason why no clear absorption bands have been assigned to the POL. Structure and stability of some other defects, like interstitial ozone molecule (ozonyl) and dioxasilirane (silicon analogy of dioxirane), have been studied. These defects are usually not considered as most important species, however their calculated formation energies are lower compared to some known defects, which indicates they might be present in silica.
From a detailed study on possible reaction mechanisms, it has been found that ozonyl might be one of the most important intermediate steps for oxygen exchange reactions. Results also show that dioxasilirane can be spontaneously created during the interaction of oxygen with lone pair defects. By exploring different reactions between oxygen and pre-existing oxygen deficiency centers (ODCs), calculations predict two kinds of passivation behaviors: single-barrier reversible mechanisms with the formation of dioxasilirane-like groups, for which the network keeps the memory of the precursory lone pair defects, and single or multiple-barrier mechanisms, for which the network loses its memory, either because of the high reverse barrier or because of a reconstruction.
Final part of this research has been devoted to experimental characterization of the response and tolerance of optical fibers loaded with oxygen under irradiation. These include experiments on commercial fiber along with canonical samples (Optical fibers developed with the intention of studying correlations between different fabrication parameters, dopant/impurity concentration and doping concentrations). Studied fibers also include rare-earth doped fibers. Najdeno v: ključnih besedah Povzetek najdenega: ...algorithm used for modeling chemical/migration reactions, GW approximation for charged electronic excitations (band structure) and... Ključne besede: Silica, DFT, GW-approximation, Bethe-Salpeter equation, NEB, defect, oxygen, oxygen excess centers, oxygen deficiency centers, optical absorption, optical fibers, radiation induced attenuation. Objavljeno: 07.05.2019; Ogledov: 2610; Prenosov: 135
Polno besedilo (13,18 MB) |