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 121 - 150 of 230
Full-Text Articles in Physics
Nanoparticle Aggregation And Relaxation Effects In Ferrofluids: Studied Through Anisotropic Light Scattering, Corneliu Rablau, Prem Vaishnava, Sudakar Chandran, Ronald Tackett, Gavin Lawes, Ratna Naik
Nanoparticle Aggregation And Relaxation Effects In Ferrofluids: Studied Through Anisotropic Light Scattering, Corneliu Rablau, Prem Vaishnava, Sudakar Chandran, Ronald Tackett, Gavin Lawes, Ratna Naik
Physics Publications
We have investigated the aggregation and dissociation dynamics of 6-nm size Fe3O4 nanoparticles coated by tetra methyl ammonium hydroxide (TMAH) and the same size γ-Fe2O3 nanoparticles precipitated inside an alginate hydrogel matrix, both in aqueous suspensions, using dc magnetic-field-induced time-dependent light scattering patterns. For the Fe3O4 ferrofluid, a strong anisotropy in light scattering was observed for light propagating perpendicular to the magnetic field. This behavior is attributed to the aggregation of the nanoparticles into chain-like and column-like structures oriented parallel to the magnetic field. A significantly different behavior is observed for the aqueous suspension of γ-Fe2O3 nanoparticles precipitated in alginate …
Stability And Magnetic Properties Of T2sin (T=Cr,Mn,1≤N≤8) Clusters, R. Robles, Shiv N. Khanna, A. W. Castleman Jr
Stability And Magnetic Properties Of T2sin (T=Cr,Mn,1≤N≤8) Clusters, R. Robles, Shiv N. Khanna, A. W. Castleman Jr
Physics Publications
First-principles studies on the geometry, electronic structure, and magnetic properties of neutral and anionic Cr2Sin and Mn2Sin (1≤n≤8) have been carried out within a gradient corrected density-functional framework. We find that Cr2Sin clusters containing up to five Si atoms and Mn2Sin clusters containing up to eight Si atoms are all marked by finite local spin moments at the transition-metal site that order ferromagnetically or antiferromagnetically depending on the size and the charged state. Our studies of the variation in the binding energy upon addition of successive Si atoms and the gap between the highest occupied molecular orbital and the lowest …
Photoelectron Spectroscopic And Theoretical Studies Of Fem−(Coronene)N (M=1,2, N=1,2) Complexes, Xiang Li, Soren Eustis, Kit H. Bowen, Anil K. Kandalam, Puru Jena
Photoelectron Spectroscopic And Theoretical Studies Of Fem−(Coronene)N (M=1,2, N=1,2) Complexes, Xiang Li, Soren Eustis, Kit H. Bowen, Anil K. Kandalam, Puru Jena
Physics Publications
Fem(coronene)n (m=1,2, n=1,2) cluster anions were generated by a laser vaporization source and studied by anion photoelectron spectroscopy. Density functional theory was used to calculate the structures and the spin multiplicities of those clusters as well as the electron affinities and photodetachment transitions. The calculated magnetic moments of Fe1(coronene)1 and Fe2(coronene)1 clusters suggest that coronene could be a suitable template on which to deposit small iron clusters and that these in turn might form the basis of an iron cluster-based magnetic material. Fe1(coronene)2 and Fe2(coronene)2 cluster anions and their corresponding neutrals prefer the sandwich-type structures, and the ground state structures …
Interaction Of Gas Molecules With Ti-Benzene Complexes, G. Chen, P. Jena, Y. Kawazoe
Interaction Of Gas Molecules With Ti-Benzene Complexes, G. Chen, P. Jena, Y. Kawazoe
Physics Publications
Using first-principles calculations based on gradient corrected density functional theory, we have studied the interaction of NH3, H2, and O2 with Ti-benzene complexes [Ti(Bz)2 and Ti2(Bz)2]. The energy barriers as the gas molecules approach the Ti-benzene complexes as well as the geometries of the ground state of these interacting complexes were obtained by starting with several initial configurations. While NH3 and H2 were found to physisorb on the Ti(Bz)2 complex, the O2 reacts with it strongly leading to dissociative chemisorption of the oxygen molecule. In contrast all the gas molecules react with the Ti2(Bz)2 complex. These studies indicate that the …
Photoelectron Spectroscopy And Theoretical Studies Of [Com(Pyrene)N]− (M=1,2 And N=1,2) Complexes, Anil K. Kandalam, Puru Jena, Xiang Li, Soren N. Eustis, Kit H. Bowen
Photoelectron Spectroscopy And Theoretical Studies Of [Com(Pyrene)N]− (M=1,2 And N=1,2) Complexes, Anil K. Kandalam, Puru Jena, Xiang Li, Soren N. Eustis, Kit H. Bowen
Physics Publications
Anion photoelectron spectroscopic experiments and density functional theory based calculations have been used to investigate the structural, electronic, and magnetic properties of neutral and anionic [Com(pyrene)n] (m,n=1–2) complexes. The calculated electron affinities and vertical transition energies of Com(pyrene)n are in good agreement with the measured values. Our results provide clear evidence for dimerization of Co atoms and formation of sandwich structures in these complexes. While the calculated spin magnetic moments of neutral Co2(pyrene)n complexes suggest a preference for ferromagnetic coupling between Co atoms, the spin magnetic moment of Co atom in Co(pyrene) and Co(pyrene)2 complexes was reduced to 1μB.
Ligand Induced Ferromagnetism In Zno Nanostructures, Qian Wang, Qiang Sun, P. Jena
Ligand Induced Ferromagnetism In Zno Nanostructures, Qian Wang, Qiang Sun, P. Jena
Physics Publications
Complementary to the experimental finding that ZnO nanoparticles become ferromagnetic when coated with N and S containing ligands such as dodecylamine and dodecanethiol [Garcia et al., Nano Lett.7, 1489 (2007)], we provide the first theoretical understanding of the origin of magnetism in ligated ZnO nanoparticles as well as the structural properties of the ligated systems by using density functional theory and generalized gradient approximation for exchange and correlation, and a cluster model for the nanoparticles. We show that N or S atoms of the ligand bind to the Zn sites. The accompanying changes in the Zn–O bond length, hybridization …
Optical Properties Of Ti3sic2 And Ti4aln3, S. Li, R. Ahuja, M. W. Barsoum, Puru Jena, B. Johansson
Optical Properties Of Ti3sic2 And Ti4aln3, S. Li, R. Ahuja, M. W. Barsoum, Puru Jena, B. Johansson
Physics Publications
The dielectric functions of the MAX phases, Ti3SiC2 and Ti4AlN3, have been determined from first principles calculations. We compared the dielectric functions and the reflectivityspectra of Ti3SiC2 and Ti4AlN3 with those of TiC and TiN. The optical spectra were analyzed by means of the electronic structure, which provides theoretical understanding of the conduction mechanism of these two phases. We found that Ti4AlN3 can be used to avoid solar heating and also increase the radiative cooling due to the increased thermal emittance as compared to TiN. Ti4AlN3 can therefore be a candidate coating material for temperature control of space vehicles.
Unique Magnetic Coupling Between Mn Doped Stannaspherenes Mn @Sn12, Anil K. Kandalam, Gang Chen, Puru Jena
Unique Magnetic Coupling Between Mn Doped Stannaspherenes Mn @Sn12, Anil K. Kandalam, Gang Chen, Puru Jena
Physics Publications
We report the density functional theory based study of the interaction between two Mn doped stannaspherenes (Mn@Sn12). The calculated results show that Mn@Sn12cluster is not only highly stable and carry a high magnetic moment, but these clusters retain their structural identity and form a stable dimer cluster. Most importantly, the magnetic coupling between the Mn@Sn12clusters depends on the relative orientation of the cages. In addition, ab initiomolecular dynamics calculations show that the dimer cluster is stable at room temperature. These results are expected to trigger further investigations on highly stable bimetallic magnetic cage complexes.
First-Principles Study Of Interaction Of Molecular Hydrogen With Li-Doped Carbon Nanotube Peapod Structures, Li Chen, Yiming Zhang, Nikhil Koratkar, Puru Jena, Saroj K. Nayak
First-Principles Study Of Interaction Of Molecular Hydrogen With Li-Doped Carbon Nanotube Peapod Structures, Li Chen, Yiming Zhang, Nikhil Koratkar, Puru Jena, Saroj K. Nayak
Physics Publications
Using first-principles density functional theory based on gradient corrected approach, we have studied interaction of H2 molecule with Li-doped carbon nanotube and nanotube based peapod structures. We find that H2 physisorbs on pure carbon nanotube, which is in agreement with earlier studies, and this binding increases when H2 binds to Li-decorated on carbon nanotube surfaces: the binding is further enhanced with Li atoms deposited on C60 doped nanotube peapod structures. The increase in binding in the latter structures arises due to charge transfer between the nanotube and C60, which further facilitates charge transfer from Li to the nanotube. Encapsulating fullerene …
Vacancy-Induced Magnetism In Zno Thin Films And Nanowires, Qian Wang, Qiang Sun, Gang Chen, Yoshiyuki Kawazoe, Puru Jena
Vacancy-Induced Magnetism In Zno Thin Films And Nanowires, Qian Wang, Qiang Sun, Gang Chen, Yoshiyuki Kawazoe, Puru Jena
Physics Publications
Extensive calculations based on density functional theory have been carried out to understand the origin of magnetism in undoped ZnO thin films as found in recent experiments. The observed magnetism is confirmed to be due to Zn, instead of O, vacancy. The main source of the magnetic moment, however, arises from the unpaired 2p electrons at O sites surrounding the Zn vacancy with each nearest-neighbor O atom carrying a magnetic moment ranging from 0.490to0.740μB. Moreover, the study of vacancy-vacancy interactions indicates that in the ground state, the magnetic moments induced by Zn vacancies prefer to ferromagnetically couple with the antiferromagnetic …
Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena
Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena
Physics Publications
By using density functional theory and the generalized gradient approximation, we show that Li-decorated cis-polyacetylene meets some of the requirements of an ideal hydrogen storage material. Unlike Ti-doped cis-polyacetylene, Li resists clustering and can reversibly store up to 10.8 wt %hydrogen in molecular form. However, molecular dynamics simulations show that Li can retain hydrogen only at cryogenic temperatures. On the other hand, B-doped cis-polyacetylene can store up to 7.5 wt % hydrogen, but it binds to hydrogen too strongly to be suitable for room temperature applications. The results are compared to those in Ti-doped cis-polyacetylene.
Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena
Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena
Physics Publications
By using density functional theory and the generalized gradient approximation, we show that Li-decorated cis-polyacetylene meets some of the requirements of an ideal hydrogen storage material. Unlike Ti-doped cis-polyacetylene, Li resists clustering and can reversibly store up to 10.8 wt %hydrogen in molecular form. However, molecular dynamics simulations show that Li can retain hydrogen only at cryogenic temperatures. On the other hand, B-doped cis-polyacetylene can store up to 7.5 wt % hydrogen, but it binds to hydrogen too strongly to be suitable for room temperature applications. The results are compared to those in Ti-doped cis-polyacetylene.
Anisotropy In The Electronic Structure Of V2gec Investigated By Soft X-Ray Emission Spectroscopy And First-Principles Theory, Martin Magnuson, Ola Wilhelmsson, Maurizio Mattesini, Sa Li, Rajeev Ahuja, Olle Eriksson, Hans Högberg, Lars Hultman, Ulf Jansson
Anisotropy In The Electronic Structure Of V2gec Investigated By Soft X-Ray Emission Spectroscopy And First-Principles Theory, Martin Magnuson, Ola Wilhelmsson, Maurizio Mattesini, Sa Li, Rajeev Ahuja, Olle Eriksson, Hans Högberg, Lars Hultman, Ulf Jansson
Physics Publications
The anisotropy of the electronic structure of ternary nanolaminate V2GeC is investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured polarization-dependent emission spectra of V L2,3, C K, Ge M1, and Ge M2,3 in V2GeC are compared with those from monocarbide VC and pure Ge. The experimental emission spectra are interpreted with calculated spectra using ab initio density-functional theory including dipole transition matrix elements. Different types of covalent chemical bond regions are revealed: V 3d-C 2p bonding at −3.8 eV, Ge 4p-C 2p bonding at −6 eV, and Ge 4p-C 2sinteraction mediated via the V 3d orbitals at −11 eV …
Yellow Luminescence In Zno Layers Grown On Sapphire, M. A. Reshchikov, J. Q. Xie, B. Hertog, A. Osinsky
Yellow Luminescence In Zno Layers Grown On Sapphire, M. A. Reshchikov, J. Q. Xie, B. Hertog, A. Osinsky
Physics Publications
We conducted a detailed study of the yellow luminescence (YL) band that has a maximum of 2.19eV at 10K in undoped and N-doped ZnO layers grown on sapphire substrates. Important characteristics of this band and the related defect are established. The YL band is attributed to a transition between a shallow donor and an acceptor with an energy level ∼0.4eV above the valence band. Quenching of the YL intensity with activation energies of 85meV and 0.4eV is observed at temperatures above 100 and 320K, respectively. The YL band is possibly due to a defect complex that may include a Znvacancy.
Temperature-Dependent Characterization Of Thin-Film Filters For Optical Communications, Corneliu Rablau, Christopher Schenk
Temperature-Dependent Characterization Of Thin-Film Filters For Optical Communications, Corneliu Rablau, Christopher Schenk
Physics Publications
The explosive increase in the demand for transmission capacity for optical communications networks has resulted in a widespread deployment of dense wavelength division multiplexing (DWDM). Thin film filters are a critical component of DWDM devices. They consist of Fabry-Perot resonant cavities obtained by vacuum deposition on a glass substrate of alternating layers of two dielectric materials of different indices of refraction. The performance requirements for these filters are determined by the density of channels to be multiplexed. For the 100 GHz ITU grid, these channels are spaced 100 GHz (0.8 nm) apart. Typical figures of merit include the insertion loss …
On The Structural And Energetic Properties Of The Hydrogen Absorber Li2mg(Nh)2, C. Moysés Araújo, Ralph H. Scheicher, Puru Jena, Rajeev Ahuja
On The Structural And Energetic Properties Of The Hydrogen Absorber Li2mg(Nh)2, C. Moysés Araújo, Ralph H. Scheicher, Puru Jena, Rajeev Ahuja
Physics Publications
The authors have performed density functional theory based calculations of several possible conformations for the crystal structure of Li2Mg(NH)2 and they confirm the α phase, resolved from both x-ray and neutron diffraction data, as the ground-state configuration. It is also found that although the N–H bond is stronger in Li2Mg(NH)2 than in Li2NH, hydrogen release from Li2Mg(NH)2/LiH mixture displays more favorable thermodynamics than that from the Li2NH∕LiH mixture. The insights gained from this seemingly counterintuitive result should prove helpful in the search for promising hydrogen storage materials.
First-Principles Study Of Magnetic Properties In V-Doped Zno, Qian Wang, Qiang Sun, Puru Jena, Zheng Hu, R. Note, Y. Kawazoe
First-Principles Study Of Magnetic Properties In V-Doped Zno, Qian Wang, Qiang Sun, Puru Jena, Zheng Hu, R. Note, Y. Kawazoe
Physics Publications
A comprehensive theoretical study of electronic and magnetic properties of V-doped ZnO in bulk as well as (112¯0)thin films has been performed using density functional theory. Vanadium atoms substituted at Zn sites show very little selectivity of site occupancy. More importantly, different geometries with ferromagnetic, ferrimagnetic, and antiferromagnetic configurations are found to be energetically nearly degenerate both in Zn1−xVxO bulk and subsurface layers of the thin film. On the other hand, V atoms couple ferromagnetically when they occupy surface sites of the thin film. The diverse magnetic behaviors in V-doped ZnO account for the many reported conflicting experimental results.
Dehydrogenation From 3d-Transition-Metal-Doped Naalh4: Prediction Of Catalysts, A. Blomqvist, C. Moysés Araújo, Puru Jena, R. Ahuja
Dehydrogenation From 3d-Transition-Metal-Doped Naalh4: Prediction Of Catalysts, A. Blomqvist, C. Moysés Araújo, Puru Jena, R. Ahuja
Physics Publications
A fundamental understanding of the role of catalysts in improving the kinetics and thermodynamics of hydrogen sorption in NaAlH4 is the key for using this material in hydrogen storage. The authors present a systematic theoretical study of energies needed to desorb hydrogen in 3dtransition metal (Sc–Cu)-doped NaAlH4. They show that Cr and Fe atoms can be far more effective catalysts than Ti in desorbing hydrogen. The role of the 3d metal atoms in improving the thermodynamics of dehydrogenation is attributed to a significant shortening of the bond length with neighboring Al atoms.
Local Electronic And Optical Behaviors Of A-Plane Gan Grown Via Epitaxial Lateral Overgrowth, J. C. Moore, V. Kasliwal, A. A. Baski, X. Ni, Ü. Özgür, Hadis Morkoç
Local Electronic And Optical Behaviors Of A-Plane Gan Grown Via Epitaxial Lateral Overgrowth, J. C. Moore, V. Kasliwal, A. A. Baski, X. Ni, Ü. Özgür, Hadis Morkoç
Physics Publications
Conductive atomic force microscopy and near-field optical microscopy (NSOM) were used to study the morphology, conduction, and optical properties of a-plane GaNfilmsgrown via epitaxial lateral overgrowth (ELO) by metal organic chemical vapor deposition. The AFM images for the coalesced ELOfilms show undulations, where the window regions appear as depressions with a high density of surface pits. At reverse bias below 12V, very low uniform conduction (2pA) is seen in the window regions. Above 20V, a lower-quality sample shows localized sites inside the window regions with significant leakage, indicating a correlation between the presence of surface pits and leakage sites. Room …
Ferromagnetic To Ferrimagnetic Crossover In Cr-Doped Gan Nanohole Arrays, Q. Wang, Q. Sun, Puru Jena, Y. Kawazoe
Ferromagnetic To Ferrimagnetic Crossover In Cr-Doped Gan Nanohole Arrays, Q. Wang, Q. Sun, Puru Jena, Y. Kawazoe
Physics Publications
Using spin-polarized density-functional theory with exchange and correlation potential, approximated by both the generalized gradient approximation (GGA) and the GGA+U methods, we show that the coupling between a pair of Cr atoms substituted in GaN nanoholes is ferromagnetic. The interaction between the two Cr atoms, each carrying an average magnetic moment of around 2.5μB, is short ranged and mediated by the neighboring N atom. As the concentration of Cr increases, clustering ensues and the coupling changes from ferromagnetic to ferrimagnetic resulting in a significant reduction in the average magnetic moment per Cr atom.
Magnetic Endohedral Metallofullerenes With Floppy Interiors, Meichun Qian, Stephen V. Ong, Shiv N. Khanna, Mark B. Knickelbein
Magnetic Endohedral Metallofullerenes With Floppy Interiors, Meichun Qian, Stephen V. Ong, Shiv N. Khanna, Mark B. Knickelbein
Physics Publications
It is shown that Gd3N@C80 is a highly magnetic and very stable motif that allows enhanced contrast magnetic resonance imaging and electric dipole moment with potential for cancer treatment. Using a synergistic approach combining Stern-Gerlach experiments in beams and first-principles electronic structure studies, it is demonstrated that an isolated Gd3N has a ground state spin moment of 23μBfollowed by a noncollinear state of 17.2μB only 88meV above the ground state. The large moment is largely due to localized f electrons. As a Gd3N is embedded inside a C80 cage, the localized felectrons maintain the magnetic character while the hybridization between …
Theoretical Study Of Deep-Defect States In Bulk Pbte And In Thin Films, Khang Hoang, S. D. Mahanti, Puru Jena
Theoretical Study Of Deep-Defect States In Bulk Pbte And In Thin Films, Khang Hoang, S. D. Mahanti, Puru Jena
Physics Publications
The nature of neutral defect states in PbTe, a narrow band-gap semiconductor, has been studied using density functional theory and supercell models. We find that the defect states associated with different substitutional impurities and native point defects found in bulk PbTe are preserved in the film geometry, but get modified as one goes from the surface to the subsurface layers and then to the bulklike layers. These modifications, which usually occur in the neighborhood of the band gap, will impact the transport properties of the films. Energetic studies of different impurities and native defects embedded in bulk PbTe and in …
Ab Initio Study Of Electronic And Magnetic Properties Of The C-Codoped Ga1−Xmnxn (101¯0) Surface, Q. Wang, Q. Sun, Puru Jena
Ab Initio Study Of Electronic And Magnetic Properties Of The C-Codoped Ga1−Xmnxn (101¯0) Surface, Q. Wang, Q. Sun, Puru Jena
Physics Publications
First principles calculations based on gradient corrected density functional theory have been carried out to study the magnetic coupling between Mn atoms in pure and carbon doped Ga1−xMnxN thin films. We show that the ground state of Mn-doped GaN (101¯0) thin film, with Mn replacing the Ga sites, is antiferromagnetic but becomes ferromagnetic when it is codoped with C. The interaction between the Mn spins via the delocalized holes introduced by codoping of C at N sites is responsible for this transition. The overlap between Mn 3d and C 2p in the spin-up band renders half-metallic character to the C …
An Ab Initio Investigation On The Endohedral Metallofullerene Gd 3 N – C 80, M. C. Qian, S. N. Khanna
An Ab Initio Investigation On The Endohedral Metallofullerene Gd 3 N – C 80, M. C. Qian, S. N. Khanna
Physics Publications
First-principles electronic structure studies on the ground state geometry and electronic and magnetic properties of bare and hydrogen coated metallofullerene Gd3N–C80 have been carried out within a density functional formalism. The correlation effects are incorporated either through a generalized gradient corrected functional or through an on-site Coulomb interaction (LDA+U). It is shown that the bare Gd3N–C80 possess a ferromagnetic ground state with a large spin moment of 21μB that is highly stable against spin fluctuations. The simulated Raman spectrum shows that the low-energy peaks are contributed by the floppy movement of N atom. As to the effect of addition of …
Ground State Structures And Photoelectron Spectroscopy Of [Co-M(Coronene)](-) Complexes, Anil K. Kandalam, Boggavarapu Kiran, Puru Jena, Xiang Li, Andrej Grubisic, Kit H. Bowen
Ground State Structures And Photoelectron Spectroscopy Of [Co-M(Coronene)](-) Complexes, Anil K. Kandalam, Boggavarapu Kiran, Puru Jena, Xiang Li, Andrej Grubisic, Kit H. Bowen
Physics Publications
A synergistic approach involving theory and experiment has been used to study the structure and properties of neutral and negatively charged cobalt-coronene [Com(coronene)] complexes. The calculations are based on density functional theory with generalized gradient approximation for exchange and correlation potential, while the experiments are carried out using photoelectron spectroscopy of mass selected anions. The authors show that the geometries of neutral and anionic Co(coronene) and Co2(coronene) are different from those of the corresponding iron-coronene complexes and that both the Co atom and the dimer prefer to occupy η2-bridge binding sites. However, the magnetic coupling between the Co atoms remains …
Structure Of Siau(16): Can A Silicon Atom Be Stabilized In A Gold Cage?, Qiang Sun, Qian Wang, Gang Chen, Puru Jena
Structure Of Siau(16): Can A Silicon Atom Be Stabilized In A Gold Cage?, Qiang Sun, Qian Wang, Gang Chen, Puru Jena
Physics Publications
Nanostructures of Au and Si as well as Au–Si hybrid structures are topics of great current interest from both scientific and technological points of view. Recent discovery of Au clusters having fullerenelike geometries and the possibility of endohedral complexes with Si atoms inside the Au cage opens new possibilities for designing Au–Si nanostructures. Using ab initio simulated annealing method we have examined the stability of Si–Au16 endohedral complex. Contrary to what we believed, we find that the endohedral configuration is metastable and the structure where Si atom binds to the exterior surface of the Au16 cage is the lowest energy …
A Simple Electric Field Probe In A Gauss's Law Laboratory, Daniel O. Ludwigsen, Gregory N. Hassold
A Simple Electric Field Probe In A Gauss's Law Laboratory, Daniel O. Ludwigsen, Gregory N. Hassold
Physics Publications
Early in our calculus-based introductory course, students are introduced to electric fields and sometimes struggle with the abstraction of a vector field. They have less familiarity with the phenomena associated with electric fields, and the connection between phenomena and mathematical formalism is weaker. Our very next topic is Gauss's law.
Structure And Bonding Of Au5m (M=Na, Mg, Al, Si, P, And S) Clusters, Chiranjib Majumder, Anil K. Kandalam, Puru Jena
Structure And Bonding Of Au5m (M=Na, Mg, Al, Si, P, And S) Clusters, Chiranjib Majumder, Anil K. Kandalam, Puru Jena
Physics Publications
The atomic and electronic structure of Au5M (M=Na, Mg, Al, Si, P, S, and Au) clusters have been investigated using generalized gradient approximation to the density functional theory. Depending on the nature of interaction with different impurity elements a structural transition from planar to nonplanar configuration has been observed in Au5M. With the exception of S, impurities with p electrons (Al, Si, P) yield nonplanar geometries of Au5M clusters, while those with selectrons (Na, Mg) yield planar geometries. The properties of Au5Scluster are anomalous: The cluster not only has a planar geometry, but also is chemically most stable with the …
Effect Of Ti And Metal Vacancies On The Electronic Structure, Stability, And Dehydrogenation Of Na3alh6: Supercell Band-Structure Formalism And Gradient-Corrected Density-Functional Theory, S. Li, Puru Jena
Physics Publications
Electronic and structural properties of sodium-aluminum hexahydride (Na3AlH6) formed during the decomposition reaction of sodium alanate (NaAlH4) and the effects of Ti catalyst are studied using supercell approach and density-functional theory. The preferred site of Ti has been determined by substituting it at both the Na and Al sites and comparing the respective formation energies. The least unfavorable site for Ti is found to be the Al site. To examine the role of Ti substitution on the desorption of hydrogen, the energy cost to remove a H atom from the vicinity of Ti was calculated and compared with that from …
Effect Of Au Coating On The Magnetic And Structural Properties Of Fe Nanoclusters For Use In Biomedical Applications: A Density-Functional Theory Study, Q. Sun, A. K. Kandalam, Q. Wang, Puru Jena, Y. Kawazoe, M. Marquez
Effect Of Au Coating On The Magnetic And Structural Properties Of Fe Nanoclusters For Use In Biomedical Applications: A Density-Functional Theory Study, Q. Sun, A. K. Kandalam, Q. Wang, Puru Jena, Y. Kawazoe, M. Marquez
Physics Publications
In this paper, we report the first systematic theoretical study of gold-coated iron nanoclusters, aiming at understanding the magnetic properties of this core-shell structure used in biomedical applications. The calculations based on density-functional theory focus on the effect of gold coating on the magnetic and structural properties of iron clusters of various sizes, and the reaction of the bare and coated iron clusters with oxygen. Our results show that the magnetic moment of iron nanocore with gold coating is still significantly higher than that in bulk Fe; the coupling between Fe atoms remained ferromagnetic and is insensitive to the thickness …