Artículos de revistas: "Spherical atoms"

1

Vlasov, G. K. "Spherical excitons in manyelectron atoms". International Journal of Infrared and Millimeter Waves 12, n.º 4 (abril de 1991): 397–429. http://dx.doi.org/10.1007/bf01009413.

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2

Bhattacharyya, S., J. K. Saha y T. K. Mukhopadhyay. "Two-electron atoms under spherical confinement". Journal of Physics: Conference Series 488, n.º 15 (10 de abril de 2014): 152012. http://dx.doi.org/10.1088/1742-6596/488/15/152012.

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3

DOLMATOV, V. K., J. P. CONNERADE, A. P. LAKSHMI y S. T. MANSON. "SPECTRAL PROPERTIES OF CONFINED ATOMS". Surface Review and Letters 09, n.º 01 (febrero de 2002): 39–43. http://dx.doi.org/10.1142/s0218625x02001926.

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The changes in energy and photoionization spectra of atoms upon confinement by a spherical environment are explored theoretically. Two kinds of confinement are considered: an endohedral confinement, such as inside the bucky-ball C 60, and an impenetrable spherical confinement of adjustable radius. We demonstrate modifications in the energy spectrum and electron correlation effects in confined atoms, the appearance, nature and origin of "confinement" resonances in photoionization spectra of such atoms, as well as new regularities in the periodic table for "compressed" atoms. These findings are of importance for basic and applied physics and chemistry of atoms, molecules, surfaces, etc.

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4

Chew, H. "Transition rates of atoms near spherical surfaces". Journal of Chemical Physics 87, n.º 2 (15 de julio de 1987): 1355–60. http://dx.doi.org/10.1063/1.453317.

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5

de-la-Huerta-Sainz, Sergio, Angel Ballesteros y Nicolás A. Cordero. "Quantum Revivals in Curved Graphene Nanoflakes". Nanomaterials 12, n.º 12 (7 de junio de 2022): 1953. http://dx.doi.org/10.3390/nano12121953.

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Graphene nanostructures have attracted a lot of attention in recent years due to their unconventional properties. We have employed Density Functional Theory to study the mechanical and electronic properties of curved graphene nanoflakes. We explore hexagonal flakes relaxed with different boundary conditions: (i) all atoms on a perfect spherical sector, (ii) only border atoms forced to be on the spherical sector, and (iii) only vertex atoms forced to be on the spherical sector. For each case, we have analysed the behaviour of curvature energy and of quantum regeneration times (classical and revival) as the spherical sector radius changes. Revival time presents in one case a divergence usually associated with a phase transition, probably caused by the pseudomagnetic field created by the curvature. This could be the first case of a phase transition in graphene nanostructures without the presence of external electric or magnetic fields.

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6

Nassour, Ayoub, Slawomir Domagala, Benoit Guillot, Theo Leduc, Claude Lecomte y Christian Jelsch. "A theoretical-electron-density databank using a model of real and virtual spherical atoms". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, n.º 4 (27 de julio de 2017): 610–25. http://dx.doi.org/10.1107/s2052520617008204.

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A database describing the electron density of common chemical groups using combinations of real and virtual spherical atoms is proposed, as an alternative to the multipolar atom modelling of the molecular charge density. Theoretical structure factors were computed from periodic density functional theory calculations on 38 crystal structures of small molecules and the charge density was subsequently refined using a density model based on real spherical atoms and additional dummy charges on the covalent bonds and on electron lone-pair sites. The electron-density parameters of real and dummy atoms present in a similar chemical environment were averaged on all the molecules studied to build a database of transferable spherical atoms. Compared with the now-popular databases of transferable multipolar parameters, the spherical charge modelling needs fewer parameters to describe the molecular electron density and can be more easily incorporated in molecular modelling software for the computation of electrostatic properties. The construction method of the database is described. In order to analyse to what extent this modelling method can be used to derive meaningful molecular properties, it has been applied to the urea molecule and to biotin/streptavidin, a protein/ligand complex.

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7

Nagy, Á. "Spherical Density Functional Theory and Atoms in Molecules". Journal of Physical Chemistry A 124, n.º 1 (30 de diciembre de 2019): 148–51. http://dx.doi.org/10.1021/acs.jpca.9b09722.

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8

Attia, Amr A. A., Alexandru Lupan y R. Bruce King. "Tetracarbalane structures: nido polyhedra and non-spherical deltahedra". Dalton Transactions 45, n.º 28 (2016): 11528–39. http://dx.doi.org/10.1039/c6dt01982j.

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The lowest energy structures of the tetracarbalanes C₄Al_n−4Me_n (n = 11, 12, 13, 14) are deltahedra having the carbon atoms at degree 4 vertices. The lowest energy structures for the smaller tetracarbalanes C₄Al_n−4Me_n (n = 6, 7, 8) have pentagonal or hexagonal open faces with all four carbon atoms at degree 3 vertices.

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9

Attia, Amr A. A., Alexandru Lupan y R. Bruce King. "Novel non-spherical deltahedra in trirhenaborane structures". New Journal of Chemistry 40, n.º 9 (2016): 7564–72. http://dx.doi.org/10.1039/c6nj01922f.

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Low-energy Cp₃Re₃B_n−3H_n−3 (7 ≤ n ≤ 12) structures are found to be Re₃B_n−3 deltahedra with internally bonded Re₃ triangles. The rhenium atoms are generally located at degree 6 to 8 vertices and the boron atoms at degree 3 to 5 vertices. Low-energy Cp₃Re₃B₂H₂ and Cp₃Re₃B₃H₃ structures are found to be trigonal bipyramids and bicapped tetrahedra, respectively.

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10

Ma, Yanfu, Xiaohui Zhang, Lina Cao y Junling Lu. "Effects of the morphology and heteroatom doping of CeO2 support on the hydrogenation activity of Pt single-atoms". Catalysis Science & Technology 11, n.º 8 (2021): 2844–51. http://dx.doi.org/10.1039/d0cy02279a.

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Doping the spherical CeO₂ support using N enhances the hydrogenation activity of Pt single atoms remarkably, which can be even higher than that of spherical CeO₂ supported Pt clusters.

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11

Balykin, V. I., V. S. Letokhov, Yu B. Ovchinnikov, A. I. Sidorov y S. V. Shul’ga. "Channeling of atoms in a standing spherical light wave". Optics Letters 13, n.º 11 (1 de noviembre de 1988): 958. http://dx.doi.org/10.1364/ol.13.000958.

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12

Downs, R. T. "Pauling's rules, in a world of non-spherical atoms". American Mineralogist 99, n.º 10 (1 de octubre de 2014): 1817. http://dx.doi.org/10.2138/am-2014-5048.

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13

HUANG, YUNG-SHENG y SY-SANG LIAW. "QUANTUM ELLIPTIC STATES OF ALKALINE ATOMS". Modern Physics Letters B 15, n.º 30 (30 de diciembre de 2001): 1467–73. http://dx.doi.org/10.1142/s021798490100338x.

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We generate the Hartree–Fock Rydberg wavefunctions of alkaline atoms using the/break B-spline finite basis method and then construct the coherent elliptic states from these spherical wavefunctions. We calculate the lifetimes of the elliptic states as a function of the eccentricities. The results are consistent with previous calculation using the quantum defect theory. The core effects play an important role for the elliptic states of high eccentricities.

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14

Alshehri, Mansoor H. "An Analytical Model for Lithium Storage in Spherical Fullerenes". Energies 15, n.º 19 (28 de septiembre de 2022): 7154. http://dx.doi.org/10.3390/en15197154.

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In this paper, the encapsulation of lithium atoms in spherical fullerenes of varying sizes is investigated. The 6–12 Lennard–Jones potential function and the continuum approximation, in which it is assumed that the atoms can be replaced with a uniform distribution across the surface of the molecules, are exploited to model the interaction energies between lithium atoms and spherical fullerenes. Thus, the total interaction energies can be approximated by applying surface integrations. The results show that for a lithium atom interacting inside a spherical fullerene, the interaction energies are minimized at a position that approaches the fullerene wall as the size of the fullerene increases. However, the results show that an external force would need to be applied to a lithium atom in order to overcome the repulsive energy barrier so that it can be encapsulated in CN fullerenes with a radius of less than 2 Å. The present study indicates that the optimal radius that gives the minimum energy for the storage of Li inside CN fullerenes occurs for a fullerene with a radius of ≈2.4 Å. Overall, this study provides an analytical formulation that may facilitate rapid computational results, and an application of this work is in the design of future high-energy-density batteries that utilize CN fullerenes.

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15

Attia, Amr A. A., Alexandru Lupan y R. Bruce King. "Cyclopentadienylironphosphacarboranes: fragility of polyhedral edges in the 11-vertex system". RSC Advances 6, n.º 2 (2016): 1122–28. http://dx.doi.org/10.1039/c5ra17070b.

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The central FeCPB_n−3 polyhedra in all of the lowest energy CpFeCHP(CH₃)B_n−3H_n−3. (n = 8 to 12) structures are the most spherical closo deltahedra with adjacent iron and phosphorus atoms and non-adjacent phosphorus and carbon atoms.

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16

Balykin, V. I., V. S. Letokhov, Yu B. Ovchinnikov y S. V. Shul'ga. "Collimation of atoms localized in a spherical standing light wave". Optics Communications 77, n.º 2-3 (junio de 1990): 152–56. http://dx.doi.org/10.1016/0030-4018(90)90426-t.

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17

Tomilin, O. B., I. V. Stankevich, E. E. Muryumin y E. V. Rodionova. "Electronic conjugation of carbon atoms in spherical and cylindrical molecules". Carbon 50, n.º 14 (noviembre de 2012): 5217–25. http://dx.doi.org/10.1016/j.carbon.2012.07.005.

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18

Starostenkov, Mikhail D., Oleg V. Yashin y Alexander V. Yashin. "Modeling the Deformation of FCC Nickel Nanowires which Contain Hydrogen Atoms". Nano Hybrids and Composites 15 (mayo de 2017): 21–25. http://dx.doi.org/10.4028/www.scientific.net/nhc.15.21.

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Using the method of molecular dynamics, FCC Ni nanowires containing hydrogen atoms in octahedral and tetrahedral pores are investigated in the course of high-speed uniaxial tensile loading along the direction <001>. The feature of structural transformations in Ni nanowires containing hydrogen is appearance on the stage of plastic deformation globular (spherical) formations consisting of hydrogen atoms

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19

HUANG, YUNG-SHENG, FANG-LING CHANG y SY-SANG LIAW. "ANALYSIS OF ALKALINE ATOMS IN ELLIPTIC STATES". International Journal of Modern Physics B 18, n.º 03 (30 de enero de 2004): 349–56. http://dx.doi.org/10.1142/s0217979204023969.

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This paper presents the coherent elliptic states (CES) of alkaline constructed from the spherical Rydberg wavefunctions generated by the B-spline method associated with Hartree–Fock approximation. To construct the elliptic orbit for alkaline is not straightforward. The core effect plays an important role for the formation of elliptic states especially in higher and lower eccentricity. When the eccentricity is not large (i.e. e=0.6), the physical quantities of CES of alkaline atoms can be theoretically calculated by the replacement with hydrogen atom.

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20

Wang, Qing Cheng, Xiao Dong Yang y Guang Rui Shang. "Fabrication of Copper-Based Superhydrophobic Surface through Template Deposition". Advanced Materials Research 915-916 (abril de 2014): 799–802. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.799.

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Experiment prepared polystyrene microspheres with a diameter of 722nm, the template of polystyrene microspheres obtained through the self-assembly. The copper atoms fill the voids of the template by electrochemical deposition, after removing template, copper surface obtain regular arrangement of spherical cave structure. Copper surface with spherical cave modified fluorosilane by chemical method, The contact angle of the surface is 156.3 ° through contact angle measuring. Superhydrophobicity of prepared copper surface is because of two important factors, one is regular microstructure of spherical cave, the other is modification of fluoroalkylsilane.

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21

Colavecchia, F. D., G. Gasaneo y D. Mitnik. "Double Photoionization of Endohedrally Confined Atoms". Journal of Atomic, Molecular, and Optical Physics 2011 (27 de diciembre de 2011): 1–6. http://dx.doi.org/10.1155/2011/817034.

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We study the double electronic emission by photon impact from ground state of two-electron atoms in the center of a model spherical fullerene, which is described by a square-well shell. Cross-sections for different well depth are computed within a separable model for the final state, and a configuration interaction state for the initial one. Triple differential cross-sections show a strong dependence on the well depth and on the energy of the emitted electrons, due to the delocalization of the electrons in the initial state. The fullerene potential also allows higher angular momenta partial waves to be included in the process, which modifies the well-known two-lobe cross-section from isolated atom.

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22

Nuris, Ahmad Anwar. "Modeling of Ferrous Metal Diffusion in Liquid Lead Using Molecular Dynamics Simulation". Computational And Experimental Research In Materials And Renewable Energy 2, n.º 1 (2 de mayo de 2019): 45. http://dx.doi.org/10.19184/cerimre.v2i1.20561.

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Modeling of Iron metal diffusion in liquid lead using molecular dynamics simulation has been done. Molecular dynamics simulations are used to predict the value of physical quantities that we want to know based on the designed material model and on the input simulation data. In this research, effect of different geometry of material models was observed to know the diffusion coefficient. The material system was iron (Fe) in liquid lead (Pb). The material models is designed using Packmol software to get the initial configuration of atom's arrangement by inputting the material's characteristics such as mass, density, volume, number of atoms. This work examines the diffusion coefficient of iron in molten lead metal with the geometric shape of the simulation system in the form of iron in molten metal for various simulation models of boxes in a box, balls in a box and balls in balls. To design simulated geometric shapes we use the Packmol program. To calculate the diffusion coefficient we use the molecular dynamics simulation method. To find out which geometry is suitable, we compare the diffusion coefficient of the simulation results with existing references. The diffusion coefficient value of the spherical iron (Fe) system in the spherical liquid lead (Pb) has the best value compared to the other two forms with an accuracy rate of 99.94% because it is influenced by the even distribution of atoms in each part.

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23

Mezincescu, Nadia, Sorina Zota y C. Vrejoiu. "Radiative Recombination for Parabolic and Spherical States in H-like Atoms". Journal de Physique II 5, n.º 12 (diciembre de 1995): 1777–92. http://dx.doi.org/10.1051/jp2:1995207.

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24

Roy, Arpan, Andrew Bah Shen Jing y Murray D. Barrett. "The trapping and detection of single atoms using a spherical mirror". New Journal of Physics 14, n.º 9 (5 de septiembre de 2012): 093007. http://dx.doi.org/10.1088/1367-2630/14/9/093007.

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25

Balykin, V. I., Yu E. Lozovik, Yu B. Ovchinnikov, A. I. Sidorov, S. V. Shul'ga y V. S. Letokhov. "One-dimensional localization of atoms in a standing spherical light wave". Journal of the Optical Society of America B 6, n.º 11 (1 de noviembre de 1989): 2178. http://dx.doi.org/10.1364/josab.6.002178.

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26

Flores-Riveros, A. y A. Rodríguez-Contreras. "Compression effects in helium-like atoms constrained by hard spherical walls". Physics Letters A 372, n.º 40 (septiembre de 2008): 6175–82. http://dx.doi.org/10.1016/j.physleta.2008.08.027.

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27

Friedberg, Richard y Jamal T. Manassah. "Electromagnetic decay modes in a spherical sample of two-level atoms". Physics Letters A 372, n.º 46 (noviembre de 2008): 6833–42. http://dx.doi.org/10.1016/j.physleta.2008.09.032.

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28

Shpatakovskaya, G. V. "Spherical electron-ion systems in semiclassical approximation: Atoms and atomic clusters". Journal of Experimental and Theoretical Physics 98, n.º 3 (marzo de 2004): 455–62. http://dx.doi.org/10.1134/1.1705696.

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29

Sen, K. D. y Paul Geerlings. "Nuclear cusp of the virial exchange energy density for spherical atoms". Journal of Chemical Physics 117, n.º 20 (22 de noviembre de 2002): 9107–10. http://dx.doi.org/10.1063/1.1515315.

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30

Rennert, P. y F. Seifert. "Scattering Properties of Non-Spherical Muffin-Tin Potentials of Surface Atoms". physica status solidi (b) 144, n.º 2 (1 de diciembre de 1987): 617–29. http://dx.doi.org/10.1002/pssb.2221440220.

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31

Toader, Ana Maria, Maria Cristina Buta, Dan Maftei, Mihai V. Putz y Fanica Cimpoesu. "Atoms in Generalized Orbital Configurations: Towards Atom-Dedicated Density Functionals". International Journal of Molecular Sciences 20, n.º 23 (26 de noviembre de 2019): 5943. http://dx.doi.org/10.3390/ijms20235943.

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Deriving a practical formula for the atomic body with generalized shell occupations, we perform a detective analysis of the radial distribution in the exchange energy, hinting at ideas about new types of density functionals, dedicated to the specifics of the electronic structure of atoms, exploiting the intrinsic spherical symmetry.

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32

Schröder, Ludger, David John Watkin, Alain Cousson, Richard Ian Cooper y Werner Paulus. "CRYSTALSenhancements: refinement of atoms continuously disordered along a line, on a ring or on the surface of a sphere". Journal of Applied Crystallography 37, n.º 4 (17 de julio de 2004): 545–50. http://dx.doi.org/10.1107/s0021889804009847.

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The programCRYSTALS[Betteridge, Carruthers, Cooper, Prout & Watkin (2003).J. Appl. Cryst.36, 1487] has been extended to include an option for the refinement of a continuous electron density distribution lying along a line, a ring or on the surface of a sphere. These additional non-atomic electron distributions can be refined in any combination with traditional anisotropically distributed spherical atoms, including the refinement of `partial' atoms overlapping with the special electron distributions.

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33

Davie, Stuart J., Peter I. Maxwell y Paul L. A. Popelier. "The long-range convergence of the energetic properties of the water monomer in bulk water at room temperature". Physical Chemistry Chemical Physics 19, n.º 31 (2017): 20941–48. http://dx.doi.org/10.1039/c7cp03183a.

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The Interacting Quantum Atoms (IQA) energy partitioning scheme has been applied to a set of liquid water largely spherical clusters (henceforth called spheres) of up to 9 Å radius, with a maximum cluster size of 113 molecules.

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34

Abkhalimov, Evgeny, Vadim Ershov y Boris Ershov. "Determination of the Concentration of Silver Atoms in Hydrosol Nanoparticles". Nanomaterials 12, n.º 18 (6 de septiembre de 2022): 3091. http://dx.doi.org/10.3390/nano12183091.

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In this work, we propose a new method for determining the concentration of silver atoms in hydrosols of nanoparticles (NPs) stabilized with various capping agents. The proposed method is based on the determination of IBT absorption in the UV region (a broad band with a weakly pronounced shoulder at ~250 nm). To determine the extinction coefficient at 250 nm, we synthesized silver nanoparticles with average sizes of 5, 10, and 25 nm, respectively. The prepared nanoparticles were characterized by TEM, HRTEM, electron diffraction, XRD, DLS, and UV–Vis spectroscopy. It has been shown that the absorption characteristics of spherical NPs are not significantly influenced by the hydrosol preparation method and the type of stabilizer used. For particles with a size of 5–25 nm, the molar extinction coefficient of Ag0 atoms was found to be equal to 3500 ± 100 L mol−1 cm−1 at a wavelength of 250 nm. The results of the theoretical calculations of the molar extinction coefficients for spherical nanoparticles are in good agreement with the experimental values. ICP-MS analysis confirmed the applicability of this method in the concentration range of 5 × 10−7–1 × 10−4 mol L−1.

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35

Ye, Zi, Jun Xie y Xing Hua Xie. "Measuring of Nanometer Oxide Powders". Advanced Materials Research 503-504 (abril de 2012): 1416–19. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1416.

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Lithium manganese oxides with a fine spherical morphology different from that of the normal composite oxides are formed after detonation wave treatment due to the very high quenching rate. Free metal atoms are first released with the decomposition of explosives, and then theses metal and oxygen atoms are rearranged, coagulated and finally crystallized into lithium manganate during the expansion of detonation process. The growth of lithium manganate via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Lithium manganate with spherical morphology and more uniform secondary particles, with smaller primary particles of diameters from 10 to 20 nm and a variety of morphologies were found.

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36

Mbadjoun, B. Tchana, J. M. Ema’a Ema’a, Jean Yomi, P. Ele Abiama, G. H. Ben-Bolie y P. Owono Ateba. "Factorization method for exact solution of the non-central modified Killingbeck potential plus a ring-shaped-like potential". Modern Physics Letters A 34, n.º 10 (28 de marzo de 2019): 1950072. http://dx.doi.org/10.1142/s021773231950072x.

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In this paper, we study the Schrödinger equation with non-central modified Killingbeck potential plus a ring-shaped-like potential problem, which is not spherically symmetric. The factorization method is used to solve the hypergeometric equation types which lead to solutions with the associate Laguerre function for the radial part and Jacobi polynomial for the polar part. We introduce the raising and lowering operators to calculate the energies eigenvalues, which show that the lack of spherical symmetry removes the degeneracy of second quantum number m which is completely expected. These obtained energies are better to explain the superposition of the energy levels of the atoms in the crystalline structure of molecules.

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37

Malenkov, G. G. "Molecular Dynamics Simulation of Argon and Argon–Water Systems". Russian Journal of Physical Chemistry A 96, n.º 7 (julio de 2022): 1376–80. http://dx.doi.org/10.1134/s0036024422070214.

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Abstract A molecular dynamics model is created for argon near the critical point. As the temperature falls at a constant density less than critical, It is established that a drop of liquid argon forms in the gas environment. This drop is not spherical, but cylindrical. Liquid argon near the melting point (110 K, density 1.513 g/cm3) is also modeled. The values of the Voronoi polyhedra volumes (VPVs) around argon atoms are calculated and their distribution is plotted. The VPV values lie in the range of 34–55 Å3, with an average value of 43.6 Å3. Argon atoms with low VPV values tend to combine with one another and form branching clusters, as is typical of atoms with high VPV values. Clusters formed by atoms with high and low VPV values are inserted into one another. Issues related to the behavior of argon atoms in argon–water systems are also considered.

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38

Joslin, C. y S. Goldman. "Quantum Monte Carlo studies of two-electron atoms constrained in spherical boxes". Journal of Physics B: Atomic, Molecular and Optical Physics 25, n.º 9 (14 de mayo de 1992): 1965–75. http://dx.doi.org/10.1088/0953-4075/25/9/003.

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39

Shneider, M. N. "Cross-sections for neutral atoms and molecules collisions with charged spherical nanoparticle". Physics of Plasmas 23, n.º 12 (diciembre de 2016): 124503. http://dx.doi.org/10.1063/1.4972078.

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40

Kim, Deok-Soo, Youngsong Cho, Joonghyun Ryu, Jae-Kwan Kim y Donguk Kim. "Anomalies in quasi-triangulations and beta-complexes of spherical atoms in molecules". Computer-Aided Design 45, n.º 1 (enero de 2013): 35–52. http://dx.doi.org/10.1016/j.cad.2012.03.005.

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41

Yablonovitch, E. y K. M. Leung. "Photonic band structure: Non-spherical atoms in the face-centered-cubic case". Physica B: Condensed Matter 175, n.º 1-3 (diciembre de 1991): 81–86. http://dx.doi.org/10.1016/0921-4526(91)90696-c.

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42

Yang, Jian, Jiao Zhang, Yong Bing Dai, Jian Bo Ma y Bao De Sun. "Correlation between the Local Melt Structure and the Dynamical Properties of Mn, Zn and Si in Liquid Al: An Ab Initio Molecular Dynamics Study". Materials Science Forum 850 (marzo de 2016): 319–27. http://dx.doi.org/10.4028/www.scientific.net/msf.850.319.

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In this study, Mn, Zn and Si elements which are the most common alloying elements in Al, were chosen as solute atoms to be analyzed. The structure of molten Al, local structure around solute atoms and diffusion of the solute atoms are studied using ab initio molecular dynamics simulations. The results show that minimum addition of a solute (1 atom) does not significantly influence the structure of liquid Al as a whole. However, the local structure around foreign atoms varies dramatically for the different solute species. The local structure around Mn is the most compact and stable among the three types of solute atoms, leading to its lower diffusion coefficient. Conversely, Si possess the highest diffusion coefficient among those three kinds of elements derive from the local structure around Si is the most relaxed structure. In summary, the close packing and stable spherical shell around the solute atoms affect their diffusion behaviors in the melt. In addition, it is suggested that more alloying elements should be investigated to corroborate the results of this study.

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43

Yang, J. C., S. Bradley y J. M. Gibson. "Rapid and Semi-automated Method for Analysis of the Number of Atoms of Ultra-small Platinum Clusters on Carbon". Microscopy and Microanalysis 6, n.º 4 (julio de 2000): 353–57. http://dx.doi.org/10.1017/s1431927602000600.

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AbstractVery high angle (~100 mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the number of atoms in a cluster on a support material. We have developed a computer program which will automatically find the location of the particles and then integrate the intensity to find the number of atoms per cluster. We have examined ultra-small Pt clusters on a C substrate by this novel mass-spectroscopic technique. We discovered that the Pt clusters maintain their three-dimensional shape, and are probably spherical.

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44

Chowdhury, Shah Tanvir ur Rahman y John P. Perdew. "Spherical vs non-spherical and symmetry-preserving vs symmetry-breaking densities of open-shell atoms in density functional theory". Journal of Chemical Physics 155, n.º 23 (21 de diciembre de 2021): 234110. http://dx.doi.org/10.1063/5.0072020.

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Gorgeski, Andreia, Aldo Felix Craievich, Leonardo Marcon Corrêa, Luciano Andrei Montoro y Guinther Kellermann. "In situstudy of the kinetics of growth of Pb nanoparticles embedded in a PbO–B2O3glass". Journal of Applied Crystallography 51, n.º 2 (1 de marzo de 2018): 395–405. http://dx.doi.org/10.1107/s1600576718001462.

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The process of growth of liquid Pb nanoparticles embedded in a lead borate glass was investigated by transmission electron microscopy (TEM) and byin situsmall-angle X-ray scattering (SAXS) during isothermal annealing at different temperatures within the 649–679 K range. A TEM study at room temperature of the glass–Pb nanoparticle composite, previously subjected to isothermal annealing, showed the presence of a number of nearly spherical Pb nanocrystals with some size dispersion. The analysis of several series of experimental SAXS curves recordedin situ, for increasing periods of time of isothermal annealing at different temperatures, allowed the authors to determine time and temperature dependences of the radius distribution functions of the growing spherical Pb nanoparticles. Since all selected annealing temperatures were higher than the melting temperature of bulk Pb, the Pb nanoparticles were in all cases in the liquid state during the whole growth process. A fast increase in the total volume of Pb droplets was observed during the initial stages of annealing, which indicated that the Pb droplets grow because of the incorporation of Pb atoms dispersed in the glass matrix. For more advanced stages of droplet growth, when the concentration of Pb atoms becomes close to its equilibrium concentration, the time dependences of the average radius, number density and total volume of Pb droplets are those predicted by the classical theory of coarsening proposed by Lifshitz–Slyosov–Wagner. Furthermore, it has been established that the Pb nanodroplets preserve their spherical shape and their relative dispersion in size through the whole coarsening process and that the activation energy for diffusion of Pb atoms and growth of Pb droplets embedded in the studied glass isEa= 2.65 ± 0.09 eV per atom.

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SAMBI, M., E. PIN y G. GRANOZZI. "DETERMINATION OF THE OVERLAYER/SUBSTRATE REGISTRY IN Ni(1 ML)/Pt(111) BY ANGLE-SCANNED PHOTOELECTRON DIFFRACTION". Surface Review and Letters 02, n.º 06 (diciembre de 1995): 787–93. http://dx.doi.org/10.1142/s0218625x95000716.

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The site (fcc or hcp) occupied by the atoms of a Ni ML deposited on Pt (111) is determined in this paper using angle-scanned photoelectron diffraction (PD). A full 2π MgK α-excited Ni-2p 3/2 PD pattern from 1-ML Ni deposited on Pt(111) is compared to single scattering cluster-spherical wave (SSC-SW) simulations and the agreement between experimental and theoretical data is quantified by R-factor analysis. From the present investigation it turns out that Ni atoms occupy hcp sites. In addition, the Ni-Pt distance has been estimated to be 2.5±0.1 Å.

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Wang, Qian, Shulong Wen, Fanhua Hao, Zheng Huang y Shuming Peng. "Rare Gas Adsorption to Silver-Exchanged Zeolites". Advances in Condensed Matter Physics 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/342525.

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The adsorption of rare gas atoms to silver aluminosilicate has been investigated using density functional theory (DFT) with the local density approximation, generalized gradient approximation, and dispersion correction. The adsorption energies of rare gas atoms to the honeycomb lattice of silver aluminosilicate were calculated, and the results are discussed. The relationship between the electric charge density distribution and the adsorption energy is discussed. It indicates that the xenon atom has the most electrons to affect the van der Waals dispersion, so it has the highest minimum charge density, strongest polarization, most spacious spherical scope, and most favorable adsorption on silver zeolites.

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Yang, J. C., S. Bradley y J. M. Gibson. "Rapid and Semi-automated Method for Analysis of the Number of Atoms of Ultra-small Platinum Clusters on Carbon". Microscopy and Microanalysis 6, n.º 4 (julio de 2000): 353–57. http://dx.doi.org/10.1007/s100050010043.

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Abstract Very high angle (~100 mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the number of atoms in a cluster on a support material. We have developed a computer program which will automatically find the location of the particles and then integrate the intensity to find the number of atoms per cluster. We have examined ultra-small Pt clusters on a C substrate by this novel mass-spectroscopic technique. We discovered that the Pt clusters maintain their three-dimensional shape, and are probably spherical.

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Guerlin, Th, H. Niedrig y M. Sternberg. "Investigation of Ion Beam Sputter Mechanisms by Electron Beam Techniques". Proceedings, annual meeting, Electron Microscopy Society of America 48, n.º 2 (12 de agosto de 1990): 386–87. http://dx.doi.org/10.1017/s0424820100135538.

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The mechanisms of unisotropic atomic emission from single crystals under ion bombardment (Ar+, E < 25keV) have been investigated by depositing the sputtered atoms in a semi-spherical collector. A subsequent determination of the thickness distributions of the deposited films by electron backscattering gives the total angular atomic emission distribution, showing maxima in certain crystallographic directions of the sputtered target crystal: Wehner spots.Several mechanisms for the appearance of spot patterns are discussed in the literature:1.For normal incidence of the ions collision cascades are assumed with finally isotropic momentum distributions within the target crystal. Then a momentum transfer to atoms near the target surface may be possible by the following models (fig. 1):1a.Collision sequences along close packed atomic chains (e.g. the <110> direction in fcc crystals). If the residual collision energy exceeds the surface binding energy the atom at the surface end of the chain is emitted into the chain direction: Focusson model (fig. 1a).1b.Emission of subsurface atoms through potential minima between surface atoms (fig. 1b), and emission of surface atoms by central collision of subsurface atoms (fig. 1c). Both processes lead to emission into preferred directions: Surface model.

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BANHART, F., N. GROBERT, M. TERRONES, J. C. CHARLIER y P. M. AJAYAN. "METAL ATOMS IN CARBON NANOTUBES AND RELATED NANOPARTICLES". International Journal of Modern Physics B 15, n.º 31 (20 de diciembre de 2001): 4037–69. http://dx.doi.org/10.1142/s0217979201007944.

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The paper reviews the present state of research in the field of metal-carbon nanocomposites and the interaction of metal atoms with graphitic structures. Metal crystals can be encapsulated within graphitic shells of cylindrical, spherical, or other geometry. Various chemical and physical production methods to generate metal containing carbon nanotubes and possible microscopic formation mechanisms are presented. In this context, the role of metals as catalysts in the formation of single-walled carbon nanotubes is discussed. The interaction of metal atoms with the graphitic lattice is of particular interest. In situ electron microscopy is used to study the behaviour of individual metal atoms in a graphitic lattice. Furthermore, novel nanostructures can be generated under electron irradiation. Finally, an overview of theoretical studies using molecular dynamics and tight binding calculations of the carbon-metal interaction is given.

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