Ab initio study of physical properties of some solid materials / Abderrazek Khireddine  

Public ISBD Titre : Ab initio study of physical properties of some solid materials Type de document : document électronique Auteurs : Abderrazek Khireddine ; Bouhemadou,A, Directeur de thèse Editeur : Setif:UFA Année de publication : 2024 Importance : 1 vol. (141 f.) Catégories : Thèses & Mémoires:Physique Mots-clés : Density functional theory (DFT)  Ternary Zintl phases  First-principles (ab initio) calculations  Electronic structure  Effective masses  Optoelectronic properties  Elastic constants  Thermoelectric coefficients Résumé : The structural, electronic, optical, elastic and thermoelectric properties of the ternary Zintl compounds Sr3GaAs3, Ba3GaAs3 and Ba2ZnP2 were studied using two complementary first-principles calculation methods, the pseudopotentials plane waves (PP-PW) and the full potential Linearized Augmented Plane wave (FP-LAPW) methods within the density function theory framework. Sr3GaAs3 and Ba3GaAs3 crystallize in an orthorhombic system, space group Pnma (no 62), while Ba2ZnP2 crystallizes in an orthorhombic system, space group Ibam (no 72). GGA-PBEsol was used to treat the exchange and correlation potential (XC) to calculate the structural and elastic properties. GGA-PBEsol and TB-mBJ were used to study its electronic and optical properties. The values of structural parameters (the parameters and volume of primitive cell) calculated agreed well with available experimental data. This indicates the reliability of our results. We have numerically estimated the elastic constants and associated properties (elastic constants Cij, Young's modulus E, shear modulus G, Poisson's modulus  and Debye temperature D) for single-crystal and polycrystalline under zero pressure and anisotropic sound velocities. The calculation results showed that the studied compounds belong to the semiconductor family, with direct band gaps for the compounds Sr3GaAs3 and Ba3GaAs3, valued at 1.271 eV and 1.285 eV, respectively, and an indirect band gap energy with a value of 1.24 eV for Ba2ZnP2. We analysed the electronic states of the energy bands using partial density diagrams of states. Optical constants were calculated in an energy range from 0 to 30 MeV. The results of the calculations showed an increase in the static dielectric constant () with a decrease in the energy impedances of the studied compounds. The thermoelectric constants of the compounds were studied using semi-classical Boltzmann transport theory. Our results indicate that Ba2ZnP2 has a best figure of merit (ZT) of 1.77 at 300 K, making it a potential candidate for thermoelectric applications Côte titre : DPH/0296 En ligne : http://dspace.univ-setif.dz:8888/jspui/bitstream/123456789/4361/1/2303.pdf Ab initio study of physical properties of some solid materials [document électronique] / Abderrazek Khireddine ; Bouhemadou,A, Directeur de thèse . - [S.l.] : Setif:UFA, 2024 . - 1 vol. (141 f.). Catégories : Thèses & Mémoires:Physique Mots-clés : Density functional theory (DFT)  Ternary Zintl phases  First-principles (ab initio) calculations  Electronic structure  Effective masses  Optoelectronic properties  Elastic constants  Thermoelectric coefficients Résumé : The structural, electronic, optical, elastic and thermoelectric properties of the ternary Zintl compounds Sr3GaAs3, Ba3GaAs3 and Ba2ZnP2 were studied using two complementary first-principles calculation methods, the pseudopotentials plane waves (PP-PW) and the full potential Linearized Augmented Plane wave (FP-LAPW) methods within the density function theory framework. Sr3GaAs3 and Ba3GaAs3 crystallize in an orthorhombic system, space group Pnma (no 62), while Ba2ZnP2 crystallizes in an orthorhombic system, space group Ibam (no 72). GGA-PBEsol was used to treat the exchange and correlation potential (XC) to calculate the structural and elastic properties. GGA-PBEsol and TB-mBJ were used to study its electronic and optical properties. The values of structural parameters (the parameters and volume of primitive cell) calculated agreed well with available experimental data. This indicates the reliability of our results. We have numerically estimated the elastic constants and associated properties (elastic constants Cij, Young's modulus E, shear modulus G, Poisson's modulus  and Debye temperature D) for single-crystal and polycrystalline under zero pressure and anisotropic sound velocities. The calculation results showed that the studied compounds belong to the semiconductor family, with direct band gaps for the compounds Sr3GaAs3 and Ba3GaAs3, valued at 1.271 eV and 1.285 eV, respectively, and an indirect band gap energy with a value of 1.24 eV for Ba2ZnP2. We analysed the electronic states of the energy bands using partial density diagrams of states. Optical constants were calculated in an energy range from 0 to 30 MeV. The results of the calculations showed an increase in the static dielectric constant () with a decrease in the energy impedances of the studied compounds. The thermoelectric constants of the compounds were studied using semi-classical Boltzmann transport theory. Our results indicate that Ba2ZnP2 has a best figure of merit (ZT) of 1.77 at 300 K, making it a potential candidate for thermoelectric applications Côte titre : DPH/0296 En ligne : http://dspace.univ-setif.dz:8888/jspui/bitstream/123456789/4361/1/2303.pdf

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Ab initio Study of simple and co-axical Nanowires for solar cell application / Haffad,Slimane

Public ISBD Titre : Ab initio Study of simple and co-axical Nanowires for solar cell application Type de document : texte imprimé Auteurs : Haffad,Slimane, Auteur ; Madani Samaha, Directeur de thèse Importance : 1 vol (123 f .) Format : 29 cm Langues : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Physique des matériaux Côte titre : DPH/0261 Ab initio Study of simple and co-axical Nanowires for solar cell application [texte imprimé] / Haffad,Slimane, Auteur ; Madani Samaha, Directeur de thèse . - [s.d.] . - 1 vol (123 f .) ; 29 cm. Langues : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Physique des matériaux Côte titre : DPH/0261

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Ab initio Study of Some Physical Properties of the Cu2MgSiS4 and Cu2MgGeS4 diamond-like semiconductors and Sr2GeN2 Polymorphs / BEDJAOUI Abdelhak  

Public ISBD Titre : Ab initio Study of Some Physical Properties of the Cu2MgSiS4 and Cu2MgGeS4 diamond-like semiconductors and Sr2GeN2 Polymorphs Type de document : texte imprimé Auteurs : BEDJAOUI Abdelhak, Auteur Editeur : Setif:UFA Année de publication : 2017 Importance : 1 vol (187 f .) Format : 29 cm Langues : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Diamond-like compound Sr2GeN2 polymorphs First-principles calculations structural parameters Elastic moduli Electronic structure  Optical properties  thermodynamic properties Index. décimale : 530 Physique Résumé : In the present work, we have explored some physical properties of the two newly synthetized quaternary diamond-like semiconductors Cu2MgSiS4 and Cu2MgGeS4, and two polymorphs of the ternary nitrides α-Sr2GeN2 and β-Sr2GeN2, using firstprinciple calculations based on the density functional theory (DFT). The exchange-correlation effects were treated within the new version of the generalized gradient approximation (GGA-PBEsol). The structural, elastic, electronic and optical properties of the two considered diamond-like semiconductors were studied in detail using two complementary first-principles approaches: the pseudopotential plane wave (PP-PW) and the full potential augmented plane wane (FP-LAPW). The calculated equilibrium structural parameters are in good agreement with the available experimental data. Single-crystal and polycrystalline elastic moduli and their related properties, including elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, elastic anisotropy indexes, Pugh’s criterion, elastic wave velocities and Debye temperature, were predicted. We find that the inclusion of the electronic exchange-correlation through the newly developed TB-mBJ improves the description of the electronic structure. The TB-mBJ yields a direct band gap (Γ-Γ) of 2.64 and 1.54 eV for Cu2MgSiS4 and Cu2MgGeS4, respectively. Frequency-dependence of the dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity, energy loss function and optical conductivity were predicted, and the origins of the observed electronic transitions were assigned. Both Cu2MgSiS4 and Cu2MgGeS4 exhibit noticeable absorption in the ultraviolet range. The structural, elastic and thermodynamic properties of the α (tetragonal) and β (orthorhombic) polymorphs of the Sr2GeN2 compound have been examined in detail using ab initio pseudopotential plane-wave calculations. Apart the structural properties at ambient conditions, all present reported results are predicted for the first time. The calculated equilibrium lattice parameters and inter-atomic bond-lengths of the considered polymorphs are in good agreement with the available experimental data. It is found that α-Sr2GeN2 is energetically more stable than β-Sr2GeN2. The two examined polymorphs are very similar in their crystal structures and have almost identical local environments. The single-crystal and polycrystalline elastic parameters and related properties, including elastic constants, bulk, shear and Young’s moduli, Poisson’s ratio, anisotropy indexes, Pugh’s criterion, elastic wave velocities and Debye temperature, have been predicted. Temperature and pressure dependence of some macroscopic properties - including the bulk modulus, volume thermal expansion coefficient, heat capacity and Debye temperature - have been evaluated using ab initio calculations combined with the quasi-harmonic Debye model. Côte titre : DPH/0207 En ligne : https://drive.google.com/file/d/1znqhYjJAUf5xV_vYR8ftRwURwdDlL9eJ/view?usp=shari [...] Format de la ressource électronique : pdf Ab initio Study of Some Physical Properties of the Cu2MgSiS4 and Cu2MgGeS4 diamond-like semiconductors and Sr2GeN2 Polymorphs [texte imprimé] / BEDJAOUI Abdelhak, Auteur . - [S.l.] : Setif:UFA, 2017 . - 1 vol (187 f .) ; 29 cm. Langues : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Diamond-like compound Sr2GeN2 polymorphs First-principles calculations structural parameters Elastic moduli Electronic structure  Optical properties  thermodynamic properties Index. décimale : 530 Physique Résumé : In the present work, we have explored some physical properties of the two newly synthetized quaternary diamond-like semiconductors Cu2MgSiS4 and Cu2MgGeS4, and two polymorphs of the ternary nitrides α-Sr2GeN2 and β-Sr2GeN2, using firstprinciple calculations based on the density functional theory (DFT). The exchange-correlation effects were treated within the new version of the generalized gradient approximation (GGA-PBEsol). The structural, elastic, electronic and optical properties of the two considered diamond-like semiconductors were studied in detail using two complementary first-principles approaches: the pseudopotential plane wave (PP-PW) and the full potential augmented plane wane (FP-LAPW). The calculated equilibrium structural parameters are in good agreement with the available experimental data. Single-crystal and polycrystalline elastic moduli and their related properties, including elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, elastic anisotropy indexes, Pugh’s criterion, elastic wave velocities and Debye temperature, were predicted. We find that the inclusion of the electronic exchange-correlation through the newly developed TB-mBJ improves the description of the electronic structure. The TB-mBJ yields a direct band gap (Γ-Γ) of 2.64 and 1.54 eV for Cu2MgSiS4 and Cu2MgGeS4, respectively. Frequency-dependence of the dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity, energy loss function and optical conductivity were predicted, and the origins of the observed electronic transitions were assigned. Both Cu2MgSiS4 and Cu2MgGeS4 exhibit noticeable absorption in the ultraviolet range. The structural, elastic and thermodynamic properties of the α (tetragonal) and β (orthorhombic) polymorphs of the Sr2GeN2 compound have been examined in detail using ab initio pseudopotential plane-wave calculations. Apart the structural properties at ambient conditions, all present reported results are predicted for the first time. The calculated equilibrium lattice parameters and inter-atomic bond-lengths of the considered polymorphs are in good agreement with the available experimental data. It is found that α-Sr2GeN2 is energetically more stable than β-Sr2GeN2. The two examined polymorphs are very similar in their crystal structures and have almost identical local environments. The single-crystal and polycrystalline elastic parameters and related properties, including elastic constants, bulk, shear and Young’s moduli, Poisson’s ratio, anisotropy indexes, Pugh’s criterion, elastic wave velocities and Debye temperature, have been predicted. Temperature and pressure dependence of some macroscopic properties - including the bulk modulus, volume thermal expansion coefficient, heat capacity and Debye temperature - have been evaluated using ab initio calculations combined with the quasi-harmonic Debye model. Côte titre : DPH/0207 En ligne : https://drive.google.com/file/d/1znqhYjJAUf5xV_vYR8ftRwURwdDlL9eJ/view?usp=shari [...] Format de la ressource électronique : pdf

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Ab initio study of some physical properties of the newly synthesized selenides TI2CDXSE4(X = Ge, Sn). / Karkour,Selma  

Public ISBD Titre : Ab initio study of some physical properties of the newly synthesized selenides TI2CDXSE4(X = Ge, Sn). Type de document : document électronique Auteurs : Karkour,Selma ; Bouhemadou,A, Directeur de thèse Editeur : Setif:UFA Année de publication : 2024 Importance : 1 vol. (100 f.) Catégories : Thèses & Mémoires:Physique Mots-clés : First-principles calculations  Spin-orbit coupling  Effective masse  DFT  FP-LAPW  GGA  TB-mBJ. Résumé : Motivated by the increasing need for high-performance semiconductor materials, we conducted a comprehensive investigation into the structural, elastic, electronic, and optical properties of two recently synthesized compounds, namely Tl2CdGeSe4 and Tl2CdSnSe4, using the full potential linearized augmented plane wave (FP-LAPW) and pseudopotential plane wave (PP-PW) employing density functional theory calculations. The calculations were carried out with the inclusion of relativistic effects, specifically accounting for spin-orbit coupling (SOC). The resulting equilibrium structural parameters obtained from the computations exhibit remarkable agreement with available measurements. It should be noted that the calculations for all the properties examined were carried out using the theoretic equilibrium lattice parameters. The obtained results for both monocrystalline and polycrystalline elastic constants indicate that the investigated compounds exhibit softness, ductility, mechanical stability, and significant structural and elastic anisotropy. By employing the Tran-Blaha modified Becke-Johnson potential and considering the inclusion of spin-orbit coupling (SOC), our calculations reveal that both Tl2CdGeSe4 and Tl2CdSnSe4 are direct bandgap semiconductors. Incorporating SOC leads to a reduction in the fundamental bandgap of Tl2CdGeSe4 from 1.123 to 0.981 eV and that of Tl2CdSnSe4 from 1.097 to 0.953 eV. The l-decomposed atom-projected densities of states were utilized to determine the individual contributions of each constituent atom to the electronic states within the energy bands. The upper valence subband predominantly arises from the Se-4p states, while the bottom of the conduction band primarily originates from the Se-4p and Ge-4p/Sn-5p states. Furthermore, frequency-dependent linear optical parameters, including the complex dielectric function, absorption coefficient, refractive index, reflectivity, and energy-loss function, were calculated across a wide energy range for electromagnetic waves polarized parallel and perpendicular to the c-axis. Efforts were made to elucidate the microscopic origins of the observed peaks and structures in the calculated optical spectra. Côte titre : DPH/0303 En ligne : http://dspace.univ-setif.dz:8888/jspui/handle/123456789/4404 Ab initio study of some physical properties of the newly synthesized selenides TI2CDXSE4(X = Ge, Sn). [document électronique] / Karkour,Selma ; Bouhemadou,A, Directeur de thèse . - [S.l.] : Setif:UFA, 2024 . - 1 vol. (100 f.). Catégories : Thèses & Mémoires:Physique Mots-clés : First-principles calculations  Spin-orbit coupling  Effective masse  DFT  FP-LAPW  GGA  TB-mBJ. Résumé : Motivated by the increasing need for high-performance semiconductor materials, we conducted a comprehensive investigation into the structural, elastic, electronic, and optical properties of two recently synthesized compounds, namely Tl2CdGeSe4 and Tl2CdSnSe4, using the full potential linearized augmented plane wave (FP-LAPW) and pseudopotential plane wave (PP-PW) employing density functional theory calculations. The calculations were carried out with the inclusion of relativistic effects, specifically accounting for spin-orbit coupling (SOC). The resulting equilibrium structural parameters obtained from the computations exhibit remarkable agreement with available measurements. It should be noted that the calculations for all the properties examined were carried out using the theoretic equilibrium lattice parameters. The obtained results for both monocrystalline and polycrystalline elastic constants indicate that the investigated compounds exhibit softness, ductility, mechanical stability, and significant structural and elastic anisotropy. By employing the Tran-Blaha modified Becke-Johnson potential and considering the inclusion of spin-orbit coupling (SOC), our calculations reveal that both Tl2CdGeSe4 and Tl2CdSnSe4 are direct bandgap semiconductors. Incorporating SOC leads to a reduction in the fundamental bandgap of Tl2CdGeSe4 from 1.123 to 0.981 eV and that of Tl2CdSnSe4 from 1.097 to 0.953 eV. The l-decomposed atom-projected densities of states were utilized to determine the individual contributions of each constituent atom to the electronic states within the energy bands. The upper valence subband predominantly arises from the Se-4p states, while the bottom of the conduction band primarily originates from the Se-4p and Ge-4p/Sn-5p states. Furthermore, frequency-dependent linear optical parameters, including the complex dielectric function, absorption coefficient, refractive index, reflectivity, and energy-loss function, were calculated across a wide energy range for electromagnetic waves polarized parallel and perpendicular to the c-axis. Efforts were made to elucidate the microscopic origins of the observed peaks and structures in the calculated optical spectra. Côte titre : DPH/0303 En ligne : http://dspace.univ-setif.dz:8888/jspui/handle/123456789/4404

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Actualisation des paramètres de la formule de masse de Bethe - Weizsäcker / Chergui, Fatiha

Public ISBD Titre : Actualisation des paramètres de la formule de masse de Bethe - Weizsäcker Type de document : texte imprimé Auteurs : Chergui, Fatiha, Auteur ; Benzaid,Djelloul, Directeur de thèse Editeur : Setif:UFA Année de publication : 2018 Importance : 1 vol (44 f .) Format : 29 cm Langues : Français (fre) Langues originales : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Formule de mass Ajustement au sens des moindres carrés AME2016 énergies de liaison nucléaires Index. décimale : 530 - Physique Résumé : Un nouvel ajustement au sens des moindres carrés des énergies de liaison des noyaux atomiques basé sur la dernière mise à jour des masses atomique d'AME2016 a été considéré. Le nouvel ensemble de paramètres de la formule de masse de Bethe- Weizsäcker, obtenu dans ce travail, peut réduire l'erreur relative dans les énergies de liaison lorsqu'il est calculé dans le cadre de la formule de masse. Un traitement spécial a été fait pour les noyaux moyens et lourds ayant des masses atomiques supérieures à 40-50 Note de contenu : Sommaire Introduction ……………………………………………………………………………………………………6 Modèle de la Goutte Liquide, Formule Semi-Empirique de Masse de Bethe- Weizsäcker ......................................................................................................... 7 1.1. Energie de Volume ................................................................................... 7 1.2. Energie de Surface .................................................................................... 8 1.3. Energie de Répulsion Coulombienne ........................................................ 9 1.4. Energie d’Asymétrie ............................................................................... 12 1.5. Energie d’Appariement .......................................................................... 16 1.6. Energie Correction de Couches............................................................... 18 Méthode de Gauss pour la Résolution des Systèmes d’Equations Linéaires ..... 20 2.1. Méthode de gauss .................................................................................. 20 2.2. Méthode des moindres carrées : ............................................................ 23 Détermination des paramètres de la formule de masse de Bethe-Weizsäcker 30 3.1. Application de la méthode des moindres carrés ..................................... 30 3.2. Données nucléaires utilisées dans ce travail et calcul des paramètres constants....................................................................................................... 33 3.3. Résolution du système linéaire............................................................... 34 3.4. Résultats et Discussion ........................................................................... 35 3.5. Comparaison avec les données tabulées des énergies de liaison ........... 36 conclusion………………………………………………………………………………………………….....42 Côte titre : MAPH/0234 Actualisation des paramètres de la formule de masse de Bethe - Weizsäcker [texte imprimé] / Chergui, Fatiha, Auteur ; Benzaid,Djelloul, Directeur de thèse . - [S.l.] : Setif:UFA, 2018 . - 1 vol (44 f .) ; 29 cm. Langues : Français (fre) Langues originales : Français (fre) Catégories : Thèses & Mémoires:Physique Mots-clés : Formule de mass Ajustement au sens des moindres carrés AME2016 énergies de liaison nucléaires Index. décimale : 530 - Physique Résumé : Un nouvel ajustement au sens des moindres carrés des énergies de liaison des noyaux atomiques basé sur la dernière mise à jour des masses atomique d'AME2016 a été considéré. Le nouvel ensemble de paramètres de la formule de masse de Bethe- Weizsäcker, obtenu dans ce travail, peut réduire l'erreur relative dans les énergies de liaison lorsqu'il est calculé dans le cadre de la formule de masse. Un traitement spécial a été fait pour les noyaux moyens et lourds ayant des masses atomiques supérieures à 40-50 Note de contenu : Sommaire Introduction ……………………………………………………………………………………………………6 Modèle de la Goutte Liquide, Formule Semi-Empirique de Masse de Bethe- Weizsäcker ......................................................................................................... 7 1.1. Energie de Volume ................................................................................... 7 1.2. Energie de Surface .................................................................................... 8 1.3. Energie de Répulsion Coulombienne ........................................................ 9 1.4. Energie d’Asymétrie ............................................................................... 12 1.5. Energie d’Appariement .......................................................................... 16 1.6. Energie Correction de Couches............................................................... 18 Méthode de Gauss pour la Résolution des Systèmes d’Equations Linéaires ..... 20 2.1. Méthode de gauss .................................................................................. 20 2.2. Méthode des moindres carrées : ............................................................ 23 Détermination des paramètres de la formule de masse de Bethe-Weizsäcker 30 3.1. Application de la méthode des moindres carrés ..................................... 30 3.2. Données nucléaires utilisées dans ce travail et calcul des paramètres constants....................................................................................................... 33 3.3. Résolution du système linéaire............................................................... 34 3.4. Résultats et Discussion ........................................................................... 35 3.5. Comparaison avec les données tabulées des énergies de liaison ........... 36 conclusion………………………………………………………………………………………………….....42 Côte titre : MAPH/0234

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Actualisation des Paramètres de la Formule Semi-Empirique de Masse de Bethe-Weizsäcker / Boussafaf, Imane  

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Airy function solution for inverted oscillator / Halima Tobbal,  

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Amelioration de la qualite de l’image mammographique pour l’aide au diagnostic du cancer de sein / Ibrahim Mamoutou  

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An improved Fuzzy C-Means clustering algorithm for medical image segmentation / Bouider ,Fahima  

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Analyse d’accidents d’insertion de reactivite (RIA) dans un reacteur de recherche / widad Koidri  

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Analyse de l’Argent par activation neutronique / Missi,Maroua

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Analyse d’un minerai de zinc par spectrométrie gamma et par XRF / Safinez Nour el Houda Meziane  

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Analyse numérique de la transmutions de neptunium sous des différents flux neutroniques / Sara Atmani

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Analyse par diffraction X et absorption atomique des particules sahariennes sensible à l'érosion éolienne / Hassiba Rabouhi

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Analyse par DRX ET SPECTROM2TRIE Mössbauer des nanopoudres Fe-Al élaborées par mécanosynthèse / Mohamed Barkat

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