animation:seminaires:2014:accueil

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animation:seminaires:2014:accueil [2017/03/10 10:02] – [Pushing the Frontiers of Ab Initio Kinetic Simulations in Heterogeneous Catalysis] cicalugaanimation:seminaires:2014:accueil [2017/03/10 10:05] (Version actuelle) – [Using Density Functional Theory to model photophysical properties of molecular compounds: some insights] cicaluga
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   * Antoine Venaille (Laboratoire de Physique, ENS de Lyon, France) \\   * Antoine Venaille (Laboratoire de Physique, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\
 +
 +**(42 participants)**
 +
  \\   \\ 
 In this talk I will discuss the observations of and the mechanisms responsible for the generation In this talk I will discuss the observations of and the mechanisms responsible for the generation
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 relevant limit of high magnetic Reynolds number. I shall conclude by speculating on whether statistical approaches may relevant limit of high magnetic Reynolds number. I shall conclude by speculating on whether statistical approaches may
 prove useful in describing the systematic evolution of the solar cycle. prove useful in describing the systematic evolution of the solar cycle.
- 
  
 ===== Differentiation control in the Shoot Apical Meristem, an inside out model ===== ===== Differentiation control in the Shoot Apical Meristem, an inside out model =====
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   * Annamaria Kiss (Laboratoires Joliot-Curie, ENS de Lyon, France) \\   * Annamaria Kiss (Laboratoires Joliot-Curie, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France)   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France)
 +
 +**(30 participants)**
  
 The Shoot Apical Meristem (SAM) is a dome structure of a few thousand cells at the origin of all above ground plant organs. In the SAM, plant hormones, such as cytokinin, control a complex gene expression network tightly regulating the amount of stem cells as well as the differentiation of their descendants. The Shoot Apical Meristem (SAM) is a dome structure of a few thousand cells at the origin of all above ground plant organs. In the SAM, plant hormones, such as cytokinin, control a complex gene expression network tightly regulating the amount of stem cells as well as the differentiation of their descendants.
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 The proposed model, in which tissue shape controls gene expression, is robust to cell division, growth and tissue deformation. It also offers a possible explanation to the emergence of new stem cell niches in growing primordia. The proposed model, in which tissue shape controls gene expression, is robust to cell division, growth and tissue deformation. It also offers a possible explanation to the emergence of new stem cell niches in growing primordia.
- 
 ===== Turbulence in Galaxy Clusters: Statistical Properties and Physical Implications ===== ===== Turbulence in Galaxy Clusters: Statistical Properties and Physical Implications =====
  
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   * Rolf Walder (Centre de Recherche Astrophysique de Lyon, ENS de Lyon, France) \\   * Rolf Walder (Centre de Recherche Astrophysique de Lyon, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France)   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France)
 +
 +**(18 participants)**
  
 Galaxy clusters (GC) are the largest virialized structures in the universe. While most of their mass is dark (matter), most of the visible (baryonic) matter is in the intra-cluster-medium (ICM), a hot, thin plasma. GC form hierarchically, i.e., small structures form first and then merge to form larger ones. The most massive objects are thus dynamically young, characterised in particular by unsettled dark matter substructures and strong ICM fluid motions. Galaxy clusters (GC) are the largest virialized structures in the universe. While most of their mass is dark (matter), most of the visible (baryonic) matter is in the intra-cluster-medium (ICM), a hot, thin plasma. GC form hierarchically, i.e., small structures form first and then merge to form larger ones. The most massive objects are thus dynamically young, characterised in particular by unsettled dark matter substructures and strong ICM fluid motions.
  
 In this talk I will present the first study of the statistical properties of turbulence in the ICM. For this purpose, I have employed a novel numerical technique based on an "Eulerian" refinement strategy, in which the GC volume is refined with progressively finer uniform nested grids (in a Matryoshka-like fashion) during its gravitational collapse. The statistical properties of the turbulence, including longitudinal and transverse structure functions of the solenoidal and compressional components of the velocity, as well as probability density functions of velocity derived and other thermodynamic quantities, are computed during the cluster merger history. Amongst others, this allows us to quantify for the first time the acceleration rate associated to stochastic processes (based on second order Fermi mechanism) as well as the effective lifetime of such processes. I will discuss this and other physical implications for turbulence based processes (e.g., amplification of magnetic fields) within the context of observational constraints.  In this talk I will present the first study of the statistical properties of turbulence in the ICM. For this purpose, I have employed a novel numerical technique based on an "Eulerian" refinement strategy, in which the GC volume is refined with progressively finer uniform nested grids (in a Matryoshka-like fashion) during its gravitational collapse. The statistical properties of the turbulence, including longitudinal and transverse structure functions of the solenoidal and compressional components of the velocity, as well as probability density functions of velocity derived and other thermodynamic quantities, are computed during the cluster merger history. Amongst others, this allows us to quantify for the first time the acceleration rate associated to stochastic processes (based on second order Fermi mechanism) as well as the effective lifetime of such processes. I will discuss this and other physical implications for turbulence based processes (e.g., amplification of magnetic fields) within the context of observational constraints. 
- 
 ===== Mouvement à long terme dans le Système Solaire ===== ===== Mouvement à long terme dans le Système Solaire =====
  
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   * Antoine Venaille (Laboratoire de Physique, ENS de Lyon, France) \\   * Antoine Venaille (Laboratoire de Physique, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\
-Les intégrations à long terme du mouvement des planètes du système solaire ont été un défi des dernières décennies. Les progrès dans ce domaine ont suivi l’évolution du perfectionnement des ordinateurs, mais aussi l’amélioration des algorithmes d’intégration numérique, qui ont abouti au développent d’intégrateurs symplectiques d’ordre élevé qui ont une bonne stabilité à long terme. En même temps, la parallélisation des algorithmes a aussi permis une réduction des temps de calculs. L’intégration numérique des équations est seulement une partie du travail, car il faut aussi déterminer avec précision les conditions initiales et paramètres du modèle par comparaisons aux observations existantes. Une fois que toutes ces étapes sont satisfaites, la principale limitation dans l’obtention d’une solution précise pour le mouvement des planètes réside dans la nature chaotique du système qui limite la validité des solutions à environ 60 millions d’années.  
  
 +**(48 participants)**
 +
 +Les intégrations à long terme du mouvement des planètes du système solaire ont été un défi des dernières décennies. Les progrès dans ce domaine ont suivi l’évolution du perfectionnement des ordinateurs, mais aussi l’amélioration des algorithmes d’intégration numérique, qui ont abouti au développent d’intégrateurs symplectiques d’ordre élevé qui ont une bonne stabilité à long terme. En même temps, la parallélisation des algorithmes a aussi permis une réduction des temps de calculs. L’intégration numérique des équations est seulement une partie du travail, car il faut aussi déterminer avec précision les conditions initiales et paramètres du modèle par comparaisons aux observations existantes. Une fois que toutes ces étapes sont satisfaites, la principale limitation dans l’obtention d’une solution précise pour le mouvement des planètes réside dans la nature chaotique du système qui limite la validité des solutions à environ 60 millions d’années. 
 ===== The behavior of iron and iron-bearing minerals in the Earth ===== ===== The behavior of iron and iron-bearing minerals in the Earth =====
  
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   * Razvan Caracas (Laboratoire de Géologie de Lyon, ENS de Lyon, France) \\   * Razvan Caracas (Laboratoire de Géologie de Lyon, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\
 +
 +**(22 participants)**
  
 Ron is a mineral physicists doing first-principles calculations based on density-functional theory and beyond (Dynamical mean field theory and Quantum Monte Carlo). He has extensively studied iron-bearing high-pressure phases, like FeO, (Mg,Fe)SiO3 perovskite and post-perovskite, and Fe-based alloys, under extreme pressures and temperatures. He produced data on elasticity and seismic properties, thermodynamics, and electrical conductivity. His recent work deals with metal-insulator transitions in FeO, the correct description of the magnetic transitions and the phase diagram of FeO, and the electrical conductivity of iron at Earth's core conditions. He is a Fellow of the American Physical Society, American Geophysical Union, and the Mineralogical Society of America, and receiver of the Dana medal of MSA in 2009. He was recently awarded an advanced ERC grant Ron is a mineral physicists doing first-principles calculations based on density-functional theory and beyond (Dynamical mean field theory and Quantum Monte Carlo). He has extensively studied iron-bearing high-pressure phases, like FeO, (Mg,Fe)SiO3 perovskite and post-perovskite, and Fe-based alloys, under extreme pressures and temperatures. He produced data on elasticity and seismic properties, thermodynamics, and electrical conductivity. His recent work deals with metal-insulator transitions in FeO, the correct description of the magnetic transitions and the phase diagram of FeO, and the electrical conductivity of iron at Earth's core conditions. He is a Fellow of the American Physical Society, American Geophysical Union, and the Mineralogical Society of America, and receiver of the Dana medal of MSA in 2009. He was recently awarded an advanced ERC grant
 based at University College London to work on high-pressure mineral physics. based at University College London to work on high-pressure mineral physics.
- 
 ===== Using Density Functional Theory to model photophysical properties of molecular compounds: some insights ===== ===== Using Density Functional Theory to model photophysical properties of molecular compounds: some insights =====
  
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   * Tangui Le Bahers (Laboratoire de Chimie, ENS de Lyon, France) \\   * Tangui Le Bahers (Laboratoire de Chimie, ENS de Lyon, France) \\
   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\   * Cerasela Calugaru (Centre Blaise Pascal, ENS de Lyon, France) \\
 +
 +**(28 participants)**
  
 The performances of Density Functional Theory (DFT) and Time Dependent DFT (TD-DFT) in the prediction of ground and excited state properties of molecular systems (both fully organic or containing d or f transition metals) will be reviewed by selected examples of compounds used in molecular devices with application ranging from hybrid photovoltaic cells to molecular spintronic. Special emphasis will be devoted to the possibility of providing a realistic description of the environmental effects (ex. solvent, absorption on a surface, encapsulation) on the overall photophysical properties of these systems by the means of theoretical methods ranging from continuum polarisable models for solvent,  cluster approaches, QM/QM’ or periodic calculations. Finally, a recently proposed index enabling to quantify the extent and magnitude of transferred charge associated to a charge transfer (CT) excitation, will be illustrated and applied to the description of CT excitations in push-pull donor-acceptor systems providing insights on its potential application for the designing and development of novel molecular materials. The performances of Density Functional Theory (DFT) and Time Dependent DFT (TD-DFT) in the prediction of ground and excited state properties of molecular systems (both fully organic or containing d or f transition metals) will be reviewed by selected examples of compounds used in molecular devices with application ranging from hybrid photovoltaic cells to molecular spintronic. Special emphasis will be devoted to the possibility of providing a realistic description of the environmental effects (ex. solvent, absorption on a surface, encapsulation) on the overall photophysical properties of these systems by the means of theoretical methods ranging from continuum polarisable models for solvent,  cluster approaches, QM/QM’ or periodic calculations. Finally, a recently proposed index enabling to quantify the extent and magnitude of transferred charge associated to a charge transfer (CT) excitation, will be illustrated and applied to the description of CT excitations in push-pull donor-acceptor systems providing insights on its potential application for the designing and development of novel molecular materials.
  
 <hidden> Centre Blaise Pascal, Maison de la modélisation de Lyon, Maison de la simulation de Lyon, Hôtel à projets </hidden> <hidden> Centre Blaise Pascal, Maison de la modélisation de Lyon, Maison de la simulation de Lyon, Hôtel à projets </hidden>
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Centre Blaise Pascal, ENS de Lyon - 46, allée d'Italie - 69364 Lyon cedex 07 - France
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