The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Laurent Pizzagalli - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulations and modeling of the stability of Noble Gas Atoms in interaction with vacancies in silicon
Computational Materials Science, 2014Co-Authors: Laurent Pizzagalli, A. Charaf-eddin, Sandrine BrochardAbstract:In order to identify the main actors during the initial steps of the formation of Noble Gas filled bubbles, we have performed an extensive investigation of a single Noble Gas Atom (helium, neon, argon, krypton, xenon) as interstitial or in interaction with a monovacancy and a divacancy in silicon. Density functional calculations in the generalized gradient approximation allowed us for determining the structure and stability of various configurations. We found that interstitial configurations are especially relevant for helium, and to a lesser extent for neon. Heavy Noble Gas species are predicted to form complexes with vacancies, except in out-of-equilibrium situations where an original bond-centered interstitial configuration is favored. Besides, we propose a model combining a repulsive interaction between the host local electronic density and the Noble Gas Atom, and an elastic description of this Atom as a deformable spherical inclusion into an homogeneous isotropic medium. This model is shown to provide an appropriate description, especially for light Noble Gas species such as helium and neon.
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Numerical simulations and modeling of the stability of Noble Gas Atoms in interaction with vacancies in silicon
Computational Materials Science, 2014Co-Authors: Laurent Pizzagalli, A. Charaf-eddin, Sandrine BrochardAbstract:In order to identify the main actors during the initial steps of the formation of Noble Gas filled bubbles, we have performed an extensive investigation of a single Noble Gas Atom (helium, neon, argon, krypton, xenon) as interstitial or in interaction with a monovacancy and a divacancy in silicon. Density functional calculations in the generalized gradient approximation allowed us for determining the structure and stability of various configurations. We found that interstitial configurations are especially relevant for helium, and to a lesser extent for neon. Heavy Noble Gas species are predicted to form complexes with vacancies, except in out-of-equilibrium situations where an original bond-centered interstitial configuration is favored. Besides, we propose a model combining a repulsive interaction between the host local electronic density and the Noble Gas Atom, and an elastic description of this Atom as a deformable spherical inclusion into an homogeneous isotropic medium. This model is shown to provide an appropriate description, especially for light Noble Gas species such as helium and neon. (C) 2014 Elsevier B.V. All rights reserved.
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First principles calculation of Noble Gas Atoms properties in 3C-SiC
Journal of Nuclear Materials, 2012Co-Authors: Laurent PizzagalliAbstract:First-principles calculations were performed to investigate the properties of single Noble Gas Atoms (He, Ne, Ar, Kr, Xe) in 3C-SiC. Three cases were considered: (i) a Noble Gas Atom in a perfect crystal, (ii) in the neighborhood of a monovacancy, (iii) and of a divacancy. For each case the stable configurations were determined, as well as their formation energies. The mobility of He, Ne and Ar interstitials was studied, and the associated migration energies were calculated. Our results were discussed and compared to available experimental or theoretical works.
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First principles calculation of Noble Gas Atoms properties in 3C–SiC
Journal of Nuclear Materials, 2012Co-Authors: A. Charaf-eddin, Laurent PizzagalliAbstract:International audienceFirst-principles calculations were performed to investigate the properties of single Noble Gas Atoms (He, Ne, Ar, Kr, Xe) in 3C-SiC. Three cases were considered: (i) a Noble Gas Atom in a perfect crystal, (ii) in the neighborhood of a monovacancy, (iii) and of a divacancy. For each case the stable configurations were determined, as well as their formation energies. The mobility of He, Ne and Ar interstitials was studied, and the associated migration energies were calculated. Our results were discussed and compared to available experimental or theoretical works
Pratim Kumar Chattaraj - One of the best experts on this subject based on the ideXlab platform.
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Noble Noble strong union gold at its best to make a bond with a Noble Gas Atom
ChemistryOpen, 2019Co-Authors: Sudip Pan, Pratim Kumar Chattaraj, Gourhari Jana, Gabriel MerinoAbstract:This Review presents the current status of the Noble Gas (Ng)-Noble metal chemistry, which began in 1977 with the detection of AuNe+ through mass spectroscopy and then grew from 2000 onwards; currently, the field is in a somewhat matured state. On one side, modern quantum chemistry is very effective in providing important insights into the structure, stability, and barrier for the decomposition of Ng compounds and, as a result, a plethora of viable Ng compounds have been predicted. On the other hand. experimental achievement also goes beyond microscopic detection and characterization through spectroscopic techniques and crystal structures at ambient temperature; for example, (AuXe4)2+(Sb2F11-)2 have also been obtained. The bonding between two Noble elements of the periodic table can even reach the covalent limit. The relativistic effect makes gold a very special candidate to form a strong bond with Ng in comparison to copper and silver. Insertion compounds, which are metastable in nature, depending on their kinetic stability, display an even more fascinating bonding situation. The degree of covalency in Ng-M (M=Noble metal) bonds of insertion compounds is far larger than that in non-insertion compounds. In fact, in MNgCN (M=Cu, Ag, Au) molecules, the M-Ng and Ng-C bonds might be represented as classical 2c-2e σ bonds. Therefore, Noble metals, particularly gold, provide the opportunity for experimental chemists to obtain sufficiently stable complexes with Ng at room temperature in order to characterize them by using experimental techniques and, with the intriguing bonding situation, to explore them with various computational tools from a theoretical perspective. This field is relatively young and, in the coming years, a lot of advancement is expected experimentally as well as theoretically.
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stable ncngnsi ng kr xe rn compounds with covalently bound c ng n unit possible isomerization of ncnsi through the release of the Noble Gas Atom
Chemistry: A European Journal, 2018Co-Authors: Sudip Pan, Gourhari Jana, Gabriel Merino, Estefania Ravell, Ximena Zarate, Edison Osorio, Pratim Kumar ChattarajAbstract:Although the Noble Gas (Ng) compounds with either Ng-C or Ng-N bonds have been reported in the literature, compounds containing both bonds are not known. The first set of systems having a C-Ng-N bonding unit is predicted herein through the analysis of stability and bonding in the NCNgNSi (Ng=Kr-Rn) family. While the Xe and Rn inserted analogues are thermochemically stable with respect to all dissociation channels, but for the one producing CNSiN and free Ng, NCKrNSi has another additional three-body dissociation channel, NCKrNSi→CN+Kr+NSi, which is exergonic by -9.8 kcal mol-1 at 298 K. This latter dissociation can be hindered by lowering the temperature. Moreover, the NCNgNSi→Ng+CNSiN dissociation is also kinetically prohibited by a quite high free energy barrier ranging from 25.2 to 39.3 kcal mol-1 , with a gradual increase in going from Kr to Rn. Therefore, these compounds are appropriate candidates for experimental realization. A detailed bonding analysis by employing natural bond orbital, electron density, energy decomposition, and adaptive natural density partitioning analyses indicates that both Ng-N and C-Ng bonds in the title compounds are covalent in nature. In fact, the latter analysis indicates the presence of delocalized 3c-3e σ-bond within the C-Ng-N moiety and a totally delocalized 5c-2e σ-bond in these compounds. This is an unprecedented bonding characteristic in the sense that the bonding pattern in Ng inserted compounds is generally represented as the presence of covalent bond in one side of Ng, and the ionic interaction in the other side. Further, the dissociation of Ng from NCNgNSi facilitates the formation of a higher energy isomer of NCNSi, CNSiN, which cannot be formed from bare NCNSi as such, because of the very high free energy barrier associated with the isomeric transformation. Therefore, in the presence of Ng Atoms it might be possible to detect the high energy isomer.
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in quest of a superhalogen supported covalent bond involving a Noble Gas Atom
Journal of Physical Chemistry A, 2015Co-Authors: Debdutta Chakraborty, Pratim Kumar ChattarajAbstract:The possibility of having neutral Xe-bound compounds mediated by some representative transition metal fluorides of general formula MX3 (where M=Ru, Os, Rh, Ir, Pd, Pt, Ag, Au and X=F) has been investigated through density functional theory based calculations. Nature of interaction between MX3 and Xe moieties has been characterized through detailed electron density, charge density and bond energy decomposition analyses. The feasibility of having compounds of general formula XeMX3 at 298 K has been predicted through thermodynamic considerations. The nature of interaction in between Xe and M Atoms is partly covalent in nature and the orbital interaction is the dominant contributor toward these interactions as suggested by energy decomposition analysis.
Ernst Meyer - One of the best experts on this subject based on the ideXlab platform.
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Van der Waals interactions and the limits of isolated Atom models at interfaces
Nature communications, 2016Co-Authors: Shigeki Kawai, Adam S. Foster, Torbjörn Björkman, Sylwia Nowakowska, Jonas Björk, Filippo Federici Canova, Lutz H. Gade, Thomas A. Jung, Ernst MeyerAbstract:Van der Waals forces are among the weakest, yet most decisive interactions governing condensation and aggregation processes and the phase behaviour of Atomic and molecular matter. Understanding the resulting structural motifs and patterns has become increasingly important in studies of the nanoscale regime. Here we measure the paradigmatic van der Waals interactions represented by the Noble Gas Atom pairs Ar-Xe, Kr-Xe and Xe-Xe with a Xe-functionalized tip of an Atomic force microscope at low temperature. Individual rare Gas Atoms were fixed at node sites of a surface-confined two-dimensional metal-organic framework. We found that the magnitude of the measured force increased with the Atomic radius, yet detailed simulation by density functional theory revealed that the adsorption induced charge redistribution strengthened the van der Waals forces by a factor of up to two, thus demonstrating the limits of a purely Atomic description of the interaction in these representative systems.
Tapan K. Ghanty - One of the best experts on this subject based on the ideXlab platform.
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how strong is the interaction between a Noble Gas Atom and a Noble metal Atom in the insertion compounds mngf m cu and ag and ng ar kr and xe
Journal of Chemical Physics, 2006Co-Authors: Tapan K. GhantyAbstract:Ab initio molecular orbital calculations have been carried out to investigate the structure and the stability of Noble Gas insertion compounds of the type MNgF (M=Cu and Ag, and Ng=Ar, Kr, and Xe) through second order Moller-Plesset perturbation method. All the species are found to have a linear structure with a Noble Gas–Noble metal bond, the distance of which is closer to the respective covalent bond length in comparison with the relevant van der Waals limit. The dissociation energies corresponding to the lowest energy fragmentation products, MF+Ng, have been found to be in the range of −231 to −398kJ∕mol. The respective barrier heights pertinent to the bent transition states (M–Ng–F bending mode) are quite high for the CuXeF and AgXeF species, although for the Ar and Kr containing species the same are rather low. Nevertheless the M–Ng bond length in MNgF compounds reported here is the smallest M–Ng bond ever predicted through any experimental or theoretical investigation, indicating strongest M–Ng inte...
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Insertion of Noble-Gas Atom (Kr and Xe) into Noble-metal molecules (AuF and AuOH): are they stable?
The Journal of chemical physics, 2005Co-Authors: Tapan K. GhantyAbstract:The structure and the stability of a new class of insertion compounds of Noble-Gas Atoms of the type AuNgX (Ng=Kr, Xe and X=F, OH) have been investigated theoretically through ab initio molecular-orbital calculations. All the species are found to have a linear structure with a Noble-Gas-Noble-metal bond, the distance of which is comparable to covalent bond length except the AuKrOH system, for which it lies in between the covalent and van der Waals limits. The dissociation energies corresponding to the lowest-energy fragmentation products, AuX+Ng have been computed to be -166.2, -276.0, -194.4, and -257.6 kJ/mol for AuXeF, AuKrF, AuXeOH, and AuKrOH, respectively, at the MP2 level of theory. The respective barrier heights corresponding to the bent transition states (Au-Ng-X bending mode) have been calculated to be 119.1, 74.9, 160.7, and 141.6 kJ/mol. However, three of these species are found to be metastable in their respective potential-energy surface, and the dissociation energies corresponding to the Au+Ng+X fragments have been calculated to be 112.9, 3.0, and 18.7 kJ/mol for AuXeF, AuKrF, and AuXeOH, respectively, at the same level of theory. An analysis of the nature of interactions involved in the Au-Ng-X systems has been performed using Bader's topological theory of Atoms-in-molecules (AIM). Geometric as well as energetic considerations along with AIM results suggest a partial covalent nature of Au-Ng bonds in these systems. This work might have important implications in the preparation of a new class of insertion compounds of Noble-Gas Atoms containing Noble-Gas-Noble-metal bond.
Shigeki Kawai - One of the best experts on this subject based on the ideXlab platform.
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Van der Waals interactions and the limits of isolated Atom models at interfaces
Nature communications, 2016Co-Authors: Shigeki Kawai, Adam S. Foster, Torbjörn Björkman, Sylwia Nowakowska, Jonas Björk, Filippo Federici Canova, Lutz H. Gade, Thomas A. Jung, Ernst MeyerAbstract:Van der Waals forces are among the weakest, yet most decisive interactions governing condensation and aggregation processes and the phase behaviour of Atomic and molecular matter. Understanding the resulting structural motifs and patterns has become increasingly important in studies of the nanoscale regime. Here we measure the paradigmatic van der Waals interactions represented by the Noble Gas Atom pairs Ar-Xe, Kr-Xe and Xe-Xe with a Xe-functionalized tip of an Atomic force microscope at low temperature. Individual rare Gas Atoms were fixed at node sites of a surface-confined two-dimensional metal-organic framework. We found that the magnitude of the measured force increased with the Atomic radius, yet detailed simulation by density functional theory revealed that the adsorption induced charge redistribution strengthened the van der Waals forces by a factor of up to two, thus demonstrating the limits of a purely Atomic description of the interaction in these representative systems.