Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- ELECTRONIC-STRUCTURE (11)
- APPROXIMATION (10)
- AB-INITIO (9)
- CLUSTERS (8)
- PHOTOELECTRON-SPECTROSCOPY (8)
-
- ATOMS (7)
- MOLECULES (7)
- ANIONS (6)
- IONIZATION ENERGIES (6)
- SPECTROSCOPY (6)
- STABILITY (6)
- AUGMENTED-WAVE METHOD (5)
- BINDING-ENERGIES (5)
- DENSITY (5)
- ENERGY (5)
- GAS-PHASE (5)
- IONS (5)
- DECKER SANDWICH (4)
- DENSITY-FUNCTIONAL THEORY (4)
- METAL-BENZENE COMPLEXES (4)
- SANDWICH CLUSTERS (4)
- Acoustics (3)
- BASIS-SETS (3)
- COMPLEXES (3)
- COUPLED-CLUSTER (3)
- ELECTRON-AFFINITIES (3)
- GOLD (3)
- NEGATIVE-IONS (3)
- SHELL STRUCTURE (3)
- TRANSITION-METAL DIATOMICS (3)
Articles 91 - 120 of 230
Full-Text Articles in Physics
First-Principles Study Of Hydrogen Adsorption In Metal-Doped Cof-10, Miao Miao Wu, Qian Wang, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
First-Principles Study Of Hydrogen Adsorption In Metal-Doped Cof-10, Miao Miao Wu, Qian Wang, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Physics Publications
Covalent organic frameworks (COFs), due to their low-density, high-porosity, and high-stability, have promising applications in gas storage. In this study we have explored the potential of COFs doped with Li and Ca metal atoms for storing hydrogen under ambient thermodynamic conditions. Using density functional theory we have performed detailed calculations of the sites Li and Ca atoms occupy in COF-10 and their interaction with hydrogen molecules. The binding energy of Li atom on COF-10 substrate is found to be about 1.0 eV and each Li atom can adsorb up to three H2 molecules. However, at high concentration, Li atoms cluster …
Negative Ions Of Transition Metal-Halogen Clusters, Kalpataru Pradhan, Gennady L. Gutsev, Purusottam Jena
Negative Ions Of Transition Metal-Halogen Clusters, Kalpataru Pradhan, Gennady L. Gutsev, Purusottam Jena
Physics Publications
A systematic density functional theory based study of the structure and spectroscopic properties of neutral and negatively chargedMXn clusters formed by a transition metal atom M (M=Sc,Ti,V) and up to seven halogen atoms X (X=F,Cl,Br) has revealed a number of interesting features: (1) Halogen atoms are bound chemically to Sc, Ti, and V for n≤nmax, where the maximal valence nmax equals to 3, 4, and 5 for Sc, Ti, and V, respectively. For n>nmax, two halogen atoms became dimerized in the neutral species, while dimerization begins at n=5, 6, and 7 for negatively charged clusters containing Sc, Ti, and …
Electronic Structure And Properties Of Isoelectronic Magic Clusters: Al13x (X=H,Au,Li,Na,K,Rb,Cs), Yeon Jae Ko, Anisha Shakya, Haopeng Wang, Andrej Grubisic, Weijun Zheng, Matthias Gotz, Gerd Gantefor, Kit H. Bowen, Puru Jena, Boggavarapu Kiran
Electronic Structure And Properties Of Isoelectronic Magic Clusters: Al13x (X=H,Au,Li,Na,K,Rb,Cs), Yeon Jae Ko, Anisha Shakya, Haopeng Wang, Andrej Grubisic, Weijun Zheng, Matthias Gotz, Gerd Gantefor, Kit H. Bowen, Puru Jena, Boggavarapu Kiran
Physics Publications
The equilibrium structure, stability, and electronic properties of the Al13X (X=H,Au,Li,Na,K,Rb,Cs) clusters have been studied using a combination of photoelectron spectroscopy experiment and density functional theory. All these clusters constitute 40 electron systems with 39 electrons contributed by the 13 Al atoms and 1 electron contributed by each of the X (X=H,Au,Li,Na,K,Rb,Cs) atom. A systematic study allows us to investigate whether all electrons contributed by the X atoms are alike and whether the structure, stability, and properties of all the magic clusters are similar. Furthermore, quantitative agreement between the calculated and the measured electron affinities and vertical detachment energies enable …
Enhanced Magnetic Moments Of Alkali Metal Coated Sc Clusters: New Magnetic Superatoms, Kalpataru Pradhan, J. Ulises Reveles, Prasenjit Sen, S. N. Khanna
Enhanced Magnetic Moments Of Alkali Metal Coated Sc Clusters: New Magnetic Superatoms, Kalpataru Pradhan, J. Ulises Reveles, Prasenjit Sen, S. N. Khanna
Physics Publications
It is shown that the magnetic moments of Sc atoms can be significantly enhanced by combining them with alkali atoms. We present results of first principles electronic structure calculations of ScNan (1≤n≤12) clusters that indicate that a ScNa12 cluster consisting of a Sc atom surrounded by 12 Na atoms forming a compact icosahedral structure has a spin magnetic moment of 3μB that is three times that of an isolated Sc atom. This unusual behavior is analyzed in terms of the filling of the supershells 1S, 1P,… controlled by the nature and size of the alkali atoms and the more localized …
Magnetic Moment And Local Moment Alignment In Anionic And/Or Oxidized Fen Clusters, D. R. Roy, R. Robles, S. N. Khanna
Magnetic Moment And Local Moment Alignment In Anionic And/Or Oxidized Fen Clusters, D. R. Roy, R. Robles, S. N. Khanna
Physics Publications
First principles studies on the ground statestructure, binding energy, spin multiplicity, and the noncollinearity of local spin moments in Fen and Fen− clusters and their oxides, viz., FenO2and FenO2− have been carried out within a density functional formalism. The ground states of Fen and Fen− clusters have collinear spins with a magnetic moment of around 3.0 μB per atom. The O2 molecule is found to be dissociatively absorbed and its most significant effect on spin occurs in Fe2, where Fe2O2 and Fe2O2− show antiferromagnetic and noncollinear spin arrangements, respectively. The calculated adiabatic electron affinity and the vertical transitions from the …
Structures Of Neutral And Anionic Au16 Clusters Revisited, Gang Chen, Qian Wang, Qiang Sun, Yoshiyuki Kawazoe, Puru Jena
Structures Of Neutral And Anionic Au16 Clusters Revisited, Gang Chen, Qian Wang, Qiang Sun, Yoshiyuki Kawazoe, Puru Jena
Physics Publications
Using the density functional theory and generalized gradient approximation for exchange and correlation potential, we have performed an extensive search to obtain the ground stategeometries of both neutral and anionic Au16 cluster by considering over 200 low lying isomers. For the neutral Au16 cluster we found a new Td compact structure to be the lowest energy configuration, which is nearly degenerate in total energy with the previously reported Cs and C2v noncage structures. While the Au16− cluster, in agreement with previous calculations, is found to have a Td hollow cage structure, an isomer with a planar structure is found to …
The Applicability Of Three-Dimensional Aromaticity In Bisnn- Zintl Analogues, Penee A. Clayborne, Ujjwal Gupta, Arthur C. Reber, Joshua J. Melko, Shiv N. Khanna, A. W. Castleman Jr.
The Applicability Of Three-Dimensional Aromaticity In Bisnn- Zintl Analogues, Penee A. Clayborne, Ujjwal Gupta, Arthur C. Reber, Joshua J. Melko, Shiv N. Khanna, A. W. Castleman Jr.
Physics Publications
Three-dimensional aromaticity is shown to play a role in the stability of deltahedral Zintl clusters and here we examine the connection between aromaticity and stability. In order to gain further insight, we have studied Zintl analogs comprised of bismuthdopedtin clusters with photoelectron spectroscopy and theoretical methods. To assign aromaticity, we examine the ring currents induced around the cage by using the nucleus independent chemical shift. In the current study, BiSn4− is a stable cluster and fits aromatic criteria, while BiSn5− is found to fit antiaromatic criteria and has reduced stability. The more stable clusters exhibit an aromatic character which originates …
Surface Photovoltage In Undoped N-Type Gan, M. A. Reshchikov, M. Foussekis, A. A. Baski
Surface Photovoltage In Undoped N-Type Gan, M. A. Reshchikov, M. Foussekis, A. A. Baski
Physics Publications
Steady-state and transient surface photovoltage (SPV) in undoped GaN is studied in vacuum and air ambient at room temperature and 400 K with a Kelvin probe. The results are explained within a phenomenological model accounting for the accumulation of photogenerated holes at the surface, capture of free electrons from the bulk over the near-surface potential barrier, and emission of electrons from surface states into the bulk. Simple analytical expressions are obtained and compared with experimental results. In particular, the proposed model explains the logarithmic decay of the SPV after stopping illumination. Internal and external mechanisms of the SPV are discussed …
Probing The Existence Of Energetically Degenerate Cluster Isomers By Chemical Tagging, Qian Wang, Qiang Sun, Puru Jena
Probing The Existence Of Energetically Degenerate Cluster Isomers By Chemical Tagging, Qian Wang, Qiang Sun, Puru Jena
Physics Publications
Current methods for identifying the ground state geometry of a cluster require synergy between theory and experiment. However, this becomes a difficult problem when the accuracy of the theoretical methods is not sufficient to distinguish between nearly degenerate isomers. Using density functional theory based calculations, we show that the near degeneracy between the planar and the cage structures can be lifted by tagging these with halogens and superhalogens moieties such as Cl and BO2. The energy of the planar Au16− isomer is lowered from 0.15 eV before tagging to 0.51–0.55 eV after tagging, thus providing a way to probe its …
Magnetism In Zno Nanowire With Fe/Co Codoping: First-Principles Density Functional Calculations, S. Ghosh, Q. Wang, G. P. Das, Puru Jena
Magnetism In Zno Nanowire With Fe/Co Codoping: First-Principles Density Functional Calculations, S. Ghosh, Q. Wang, G. P. Das, Puru Jena
Physics Publications
Using first-principles density functional calculations, at both generalized gradient approximation (GGA) and GGA+U levels we have investigated the electronic structure and magnetic properties of Fe/Co codoped ZnO nanowire. Here we have addressed some of the key issues such as, the preferable sites that Fe/Co can occupy, the coupling mechanism, and role of defects in coupling. We found that the spin alignment between the transition-metal atoms depends on their location. When Fe and Co atoms are nearest neighbors on the outer surface of the nanowire along [0001] direction is the lowest energy configuration with ferrimagnetic (FiM) ground state. At GGA level …
Communications: Chain And Double-Ring Polymeric Structures: Observation Of Alnh3n+1− (N=4–8) And Al4h14, Xiang Li, Andrej Grubisic, Kit H. Bowen, Anil K. Kandalam, Boggavarapu Kiran, Gerd Gantefor, Puru Jena
Communications: Chain And Double-Ring Polymeric Structures: Observation Of Alnh3n+1− (N=4–8) And Al4h14, Xiang Li, Andrej Grubisic, Kit H. Bowen, Anil K. Kandalam, Boggavarapu Kiran, Gerd Gantefor, Puru Jena
Physics Publications
A pulsed arc discharge source was used to prepare gas-phase, aluminum hydride cluster anions, AlnHm−, exhibiting enhanced hydrogen content. The maximum number of hydrogen atoms in AlnHm− species was m=3n+1 for n=5–8, i.e., AlnH3n+1−, and m=3n+2 for n=4, i.e., Al4H14−, as observed in their mass spectra. These are the most hydrogen-rich aluminum hydrides to be observed thus far, transcending the 3:1 hydrogen-to-aluminum ratio in alane. Even more striking, ion intensities for AlnHm− species with m=3n+1 and m=3n+2 hydrogen atoms were significantly higher than those of nearby AlnHm− mass peaks for which m<3n+1, i.e., the ion intensities for AlnH3n+1− and for Al4H14− deviated from the roughly bell-shaped ion intensity patterns seen for most AlnHm−species, in which m ranges from 1 to 3n. Calculations based on density functional theory showed that AlnH3n+1− clusters have chain and/or double-ring polymericstructures.
Introducing Students To Raman Spectroscopy As A Research Tool, Bahram Roughani, David Warner, Uma Ramabadran
Introducing Students To Raman Spectroscopy As A Research Tool, Bahram Roughani, David Warner, Uma Ramabadran
Physics Publications
We describe an experiment designed as an upper level physics laboratory that introduces students to Raman Scattering of electronic materials and research methodology. This experiment is an effective approach in demonstrating the relationship between the Raman intensity of the scattered light from crystals and symmetry dependent Raman selection rules. In our measurements we alter the angle between the crystal axis and the polarization of the incident laser beam by sample rotation. The three dimensional plot of the intensity profile versus the theoretical model is used to distinguish between various crystal plans of the same electronic material. This experiment combines knowledge …
Choose Wisely: Static Or Kinetic Friction—The Power Of Dimensionless Plots, Daniel O. Ludwigsen, Kathryn A. Svinarich
Choose Wisely: Static Or Kinetic Friction—The Power Of Dimensionless Plots, Daniel O. Ludwigsen, Kathryn A. Svinarich
Physics Publications
Consider a problem of sliding blocks, one stacked atop the other, resting on a friction-less table. If the bottom block is pulled horizontally, nature makes a choice: if the applied force is small, static friction between the blocks accelerates the blocks together, but with a large force the blocks slide apart. In that case, kinetic friction still forces the upper block forward but with less acceleration than the lower block. The choice, then, lies in the relative terms—what is meant by small and large? After a confusing experience during a recent exam, we’ve found a demonstration and graphical presentation that …
Origin Of The Anatase To Rutile Conversion Of Metal-Doped Tio2, Sa Li, Puru Jena
Origin Of The Anatase To Rutile Conversion Of Metal-Doped Tio2, Sa Li, Puru Jena
Physics Publications
Extensive calculations using density functional theory enable us to explain the origin of the surprising room-temperature conversion of anatase to rutile phase of TiO2 when doped with Co and Ni, but not with Cu. Contrary to earlier suggestion, neither high spin nor strain of the transition metals is found to be responsible for this phase conversion. The driving mechanism, instead, is attributed to the increased interaction between Co and Ni atoms forming a linear chain in the rutile phase. We predict that Cr and Mn which have even larger spins than Co and Ni cannot induce this phase conversion.
Magnetic Properties Of Transition-Metal-Doped Zn1−Xtxo (T=Cr, Mn, Fe, Co, And Ni) Thin Films With And Without Intrinsic Defects: A Density Functional Study, Qian Wang, Qiang Sun, Puru Jena, Y. Kawazoe
Magnetic Properties Of Transition-Metal-Doped Zn1−Xtxo (T=Cr, Mn, Fe, Co, And Ni) Thin Films With And Without Intrinsic Defects: A Density Functional Study, Qian Wang, Qiang Sun, Puru Jena, Y. Kawazoe
Physics Publications
Theoretical calculations based on density-functional theory and generalized gradient approximation have been carried out in studying the electronic structure and magnetic properties of transition-metal-doped Zn1−xTxO (T=Cr, Mn, Fe, Co, and Ni) (112¯0) thin films systematically with and without intrinsic point defects (e.g., vacancies and interstitials), and as function of concentration and distribution of dopants and vacancies. Using large supercells and geometry optimization without symmetry constraint, we are able to determine the sites that metal atoms prefer to occupy, their tendency to cluster, the preferred magnetic coupling between magnetic moments at transition-metal sites, and the effect of intrinsic point defects on …
Electronic Behavior Of The Zn- And O-Polar Zno Surfaces Studied Using Conductive Atomic Force Microscopy, J. C. Moore, S. M. Kenny, C. S. Baird, H. Morkoç, A. A. Baski
Electronic Behavior Of The Zn- And O-Polar Zno Surfaces Studied Using Conductive Atomic Force Microscopy, J. C. Moore, S. M. Kenny, C. S. Baird, H. Morkoç, A. A. Baski
Physics Publications
We have used conducting atomic force microscopy (CAFM) to study the morphology and electronic behavior of as-received and air-annealed (0001) Zn- and (0001¯) O-polar surfaces of bulk ZnO. Both polar surfaces exhibit relatively flat morphologies prior to annealing, which rearrange to form well-defined steps upon annealing in air at 1050 °C for 1 h. Long-term exposure to air results in surface layer pitting and the destruction of steps for both the as-received and air-annealed (0001¯)surfaces, indicating its enhanced reactivity relative to the (0001) surface. CAFM I-V spectra for polar surfaces are similar and indicate Ohmic to rectifying behavior that depends …
Magnetic Response Of Core-Shell Cobalt Ferrite Nanoparticles At Low Temperature, K. Maaz, M. Usman, S. Karim, A. Mumtaz, S. K. Hasanain, M. F. Bertino
Magnetic Response Of Core-Shell Cobalt Ferrite Nanoparticles At Low Temperature, K. Maaz, M. Usman, S. Karim, A. Mumtaz, S. K. Hasanain, M. F. Bertino
Physics Publications
Cobaltferritenanoparticles (size: 26±4nm) have been synthesized by coprecipitation route. The coercivity of nanoparticles follows a simple model of thermal activation of particle moments over the anisotropy barrier in the temperature range of 30–300K in accordance with Kneller’s law; however, at low temperatures (
Photoelectron Imaging And Theoretical Investigation Of Bimetallic Bi1–2ga−0–2 And Pb−1–4 Cluster Anions, M. A. Sobhy, J. Ulises Reveles, Ujjwal Gupta, Shiv N. Khanna, A. W. Castleman Jr.
Photoelectron Imaging And Theoretical Investigation Of Bimetallic Bi1–2ga−0–2 And Pb−1–4 Cluster Anions, M. A. Sobhy, J. Ulises Reveles, Ujjwal Gupta, Shiv N. Khanna, A. W. Castleman Jr.
Physics Publications
We present the results of photoelectron velocity-map imaging experiments for the photodetachment of small negatively charged BimGan (m=1–2, n=0–2), and Pbn (n=1–4) clusters at 527 nm. The photoelectron images reveal new features along with their angular distributions in the photoelectron spectra of these clusters. We report the vertical detachment energies of the observed multiple electronic bands and their respective anisotropy parameters for the BimGan and Pbn clusters derived from the photoelectron images. Experiments on the BiGan clusters reveal that the electron affinity increases with the number of Ga atoms from n=0 to 2. The BiGa−2 cluster is found to be …
Doping Induced Anisotropic Growth In C60, Miao Miao Wu, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Doping Induced Anisotropic Growth In C60, Miao Miao Wu, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Physics Publications
Using density functional theory with generalized gradient approximation for exchange and correlation energy, we show that substitution of a Si atom at one of the C sites in C60 not only allows C59Si to have a hydrophobic head with a hydrophilic tail but also the Si atom acts as a seed for anisotropic growth of the heterofullerene. This is demonstrated by interacting C59Si with N7Sc and B8Si. The resulting complex structures exhibit enhanced electric dipole moments and anisotropy. Thus, doping induced anisotropic growth of nanostructures provides a novel route for the synthesis of bifunctional particles with atomic-level control on selectivity …
Al13h−: Hydrogen Atom Site Selectivity And The Shell Model, A. Grubisic, X. Li, S. T. Stokes, K. Vetter, G. F. Ganteför, K. H. Bowen, P. Jena, B. Kiran, R. Burgert, H. Schnöckel
Al13h−: Hydrogen Atom Site Selectivity And The Shell Model, A. Grubisic, X. Li, S. T. Stokes, K. Vetter, G. F. Ganteför, K. H. Bowen, P. Jena, B. Kiran, R. Burgert, H. Schnöckel
Physics Publications
Using a combination of anion photoelectron spectroscopy and density functional theory calculations, we explored the influence of the shell model on H atom site selectivity in Al13H−. Photoelectron spectra revealed that Al13H− has two anionic isomers and for both of them provided vertical detachment energies (VDEs). Theoretical calculations found that the structures of these anionic isomers differ by the position of the hydrogen atom. In one, the hydrogen atom is radially bonded, while in the other, hydrogen caps a triangular face. VDEs for both anionic isomers as well as other energetic relationships were also calculated. Comparison of the measured versus …
Functionalized Heterofullerenes For Hydrogen Storage, Qiang Sun, Qian Wang, Puru Jena
Functionalized Heterofullerenes For Hydrogen Storage, Qiang Sun, Qian Wang, Puru Jena
Physics Publications
Using density functional theory, we show that Li decorated B doped heterofullerene (Li12C48B12) has the following desired properties of a hydrogen storagematerial. (1) The Li atoms remain isolated. (2) Through charge transfer to electron deficient C48B12 heterofullerene, the Li atoms become positively charged. (3) Each Li atom is able to bind up to three H2molecules, which remain in molecular form, and the binding energies of successive H2molecules are in the range of 0.135–0.172 eV/H2, suitable for ambient temperature storage. (4) The gravimetric density reaches the 9 wt % limit necessary for applications in the mobile industry.
Photoadsorption And Photodesorption For Gan, M. Foussekis, A. A. Baski, Michael A. Reshchikov
Photoadsorption And Photodesorption For Gan, M. Foussekis, A. A. Baski, Michael A. Reshchikov
Physics Publications
The effect of an ambient environment on the surface photovoltage and photoluminescence observed for GaN is studied. In air ambient the upward band bending gradually increases under UVillumination and is explained by the photoinduced chemisorption of surface adsorbates. Specifically, the increase in negative surface charge is consistent with the transfer of electrons from surface states or bulk to oxygen species physisorbed at the GaNsurface. In contrast, the upward band bending gradually decreases in vacuum under UVillumination and can be explained by the photoinduced desorption of these species. The photoadsorption and photodesorption of negatively charged species cause the surface depletion region …
Mg-Doped Gan Nanostructures: Energetics, Magnetism, And H2 Adsorption, Qian Wang, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Mg-Doped Gan Nanostructures: Energetics, Magnetism, And H2 Adsorption, Qian Wang, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Physics Publications
Using density functional theory and generalized gradient approximation for exchange and correlation potential we show that Mg-doped GaN nanocages and nanotubes can be magnetic with Mg-contributed spins distributed over the neighboring N sites. Mg atoms show no tendency for clustering due to the positive charge residing on them; they can trap hydrogen in molecular form via the charge polarization mechanism. The binding energies of hydrogen lie in the range of 0.1–0.2 eV/H2, which are ideal for storage applications under ambient thermodynamic conditions.
Highly Efficient (Cs8v) Superatom-Based Spin-Polarizer, Haiying He, Ravindra Pandey, J. Ulises Reveles, Shiv N. Khanna, Shashi P. Karna
Highly Efficient (Cs8v) Superatom-Based Spin-Polarizer, Haiying He, Ravindra Pandey, J. Ulises Reveles, Shiv N. Khanna, Shashi P. Karna
Physics Publications
Quantum transport through molecules and the possibility to manipulate spin has generated tremendous excitement. Here, we demonstrate unusual spin transport through a molecule of twoCs8V magnetic superatoms. Calculations based on density functional theory and nonequilibrium Green’s function methods find a much higher current for the spin-down charge carriers relative to the spin-up carriers in the model Au–(Cs8V)–(Cs8V)–Au device system with almost 100% spin polarization, indicating a highly efficient spin polarizer. The new behavior is rooted in strong coupling of the localized magnetic core on V and the itinerant electrons of the Cs shell atoms leading to nearly full spin polarization.
Magnetism In Assembled And Supported Silicon Endohedral Cages: First-Principles Electronic Structure Calculations, R. Robles, Shiv N. Khanna
Magnetism In Assembled And Supported Silicon Endohedral Cages: First-Principles Electronic Structure Calculations, R. Robles, Shiv N. Khanna
Physics Publications
First principles electronic structure calculations on a free CrSi12cluster, a (CrSi12)2 dimer, and CrSi12 clusters supported on Si(111) surfaces have been carried out within a gradient corrected density functional formalism using a supercell approach. The ground state of CrSi12 is a Cr centered hexagonal biprism of Si atoms in which the Cr spin moment is completely quenched. As two CrSi12 motifs are brought together, they form different composite units depending on initial direction of approach and, in most cases, the composite cluster is found to have a net spin moment. Cluster assemblies obtained by depositing CrSi12 motifs on a Si(111) …
Stable T2sin (T=Fe,Co,Ni,1≤N≤8) Cluster Motifs, R. Robles, S. N. Khanna
Stable T2sin (T=Fe,Co,Ni,1≤N≤8) Cluster Motifs, R. Robles, S. N. Khanna
Physics Publications
First principles studies on the geometry, electronic structure, and magnetic properties of neutral and anionic Fe2Sin, Co2Sin, and Ni2Sin (1≤n≤8) clusters have been carried out within a gradient corrected density functional framework. It is shown that these clusters display a variety of magnetic species with varying magnetic moment and different magnetic coupling between the two transition metal atoms. While Fe2Sin clusters are mostly ferromagnetic with large moments, Ni2Sin clusters are mostly nonmagnetic. Our studies of the variation of the binding energy upon addition of successive Si atoms and the gap between the highest occupied molecular orbital and the lowest unoccupied …
Superhalogen Properties Of Cufn Clusters, Q. Wang, Q. Sun, P. Jena
Superhalogen Properties Of Cufn Clusters, Q. Wang, Q. Sun, P. Jena
Physics Publications
A first-principles calculation based on gradient corrected density functional theory reveals unusual properties of a Cu atom interacting with F. Up to six F atoms are bound to a single Cu atom with electron affinities steadily rising as successive F atoms are attached, reaching a peak value of 7.2 eV in CuF5. The large energy gaps between the highest occupied and lowest unoccupied molecular orbitals, both in neutral and anionic form, provide further evidence of their stability. These unusual properties brought about by involvement of inner shell 3d-electrons not only allow CuFn to belong to the class of superhalogens but …
Stabilizing A 22 Karat Nanogolden Cage, Q. Wang, Q. Sun, P. Jena
Stabilizing A 22 Karat Nanogolden Cage, Q. Wang, Q. Sun, P. Jena
Physics Publications
Since the discovery of C60 fullerene, considerable efforts have been devoted to find other elements with similar hollow cage structures. However, search for hollow metallic cages with a diameter similar to that of C60 fullerene has been elusive. We describe a procedure for the rational design of metallic cages by suitably choosing their size, composition, and charge state. A 22 karat nanogolden cage with a diameter of about 8.5 Å and consisting of 12 Al and 20 Au atoms is found to be metastable, which can be stabilized by embedding a Mn4 cluster. In contrast to bulk Mn, which is …
Magnetic-Field-Induced Optical Anisotropy In Ferrofluids: A Time-Dependent Light-Scattering Investigation, Corneliu Rablau, Prem Vaishnava, Sudakar Chandran, Ronald Tackett, Gavin Lawes, Ratna Naik
Magnetic-Field-Induced Optical Anisotropy In Ferrofluids: A Time-Dependent Light-Scattering Investigation, Corneliu Rablau, Prem Vaishnava, Sudakar Chandran, Ronald Tackett, Gavin Lawes, Ratna Naik
Physics Publications
We report an experimental investigation of time dependent anisotropic light scattering by an aqueous suspension of tetramethyl ammonium hydroxide coated Fe3O4 nanoparticles (∼6nm) under the ON-OFF transient of an external dc magnetic field. The study employs the synchronized recording and measurement of the two magnetic-field-induced light-scattering patterns produced by two identical orthogonal He-Ne laser beams passing through the ferrofluid sample and propagating parallel and perpendicular to the applied field, respectively. From these patterns, we extract the time dependence of the induced optical anisotropy, which provides a measure of the characteristic time scale and kinematic response for field-induced …
Magnetic-Field-Induced Optical Anisotropy In Ferrofluids: A Time-Dependent Light-Scattering Investigation, Corneliu Rablau, Prem Vaishnava, Chandran Sudakar, Ronald Tackett, Gavin Lawes, Ratna Naik
Magnetic-Field-Induced Optical Anisotropy In Ferrofluids: A Time-Dependent Light-Scattering Investigation, Corneliu Rablau, Prem Vaishnava, Chandran Sudakar, Ronald Tackett, Gavin Lawes, Ratna Naik
Physics Publications
We report an experimental investigation of time dependent anisotropic light scattering by an aqueous suspension of tetramethyl ammonium hydroxide coated Fe3O4 nanoparticles (∼6nm) under the ON-OFF transient of an external dc magnetic field. The study employs the synchronized recording and measurement of the two magnetic-field-induced light-scattering patterns produced by two identical orthogonal He-Ne laser beams passing through the ferrofluid sample and propagating parallel and perpendicular to the applied field, respectively. From these patterns, we extract the time dependence of the induced optical anisotropy, which provides a measure of the characteristic time scale and kinematic response for field-induced structure formation in …