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Full-Text Articles in Physics
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 …
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.
Structure And Stability Of Co-N(Pyridine)(M)(-) Clusters: Absence Of Metal Inserted Structures, B. Douglas Edmonds, A. K. Kandalam, S. N. Khanna, X. Li, A. Grubisic, I. Khanna, K. H. Bowen
Structure And Stability Of Co-N(Pyridine)(M)(-) Clusters: Absence Of Metal Inserted Structures, B. Douglas Edmonds, A. K. Kandalam, S. N. Khanna, X. Li, A. Grubisic, I. Khanna, K. H. Bowen
Physics Publications
A synergistic approach combining the experimental photoelectron spectroscopy and theoretical electronic structure studies is used to probe the geometrical structure and the spin magnetic moment of Con(pyridine)−m clusters. It is predicted that the ground state of Co(pyridine)− is a structure where the Co atom is inserted in a CH bond. However, the insertion is marked by a barrier of 0.33eV that is not overcome under the existing experimental conditions resulting in the formation of a structure where Co occupies a site above the pyridine plane. For Co2(pyridine)−, a ground-state structure is predicted in which the Co2 diametric moiety is inserted …
Formation And Properties Of Halogenated Aluminum Clusters, D. E. Bergeron, A. W. Castleman Jr., T. Morisato, S. N. Khanna
Formation And Properties Of Halogenated Aluminum Clusters, D. E. Bergeron, A. W. Castleman Jr., T. Morisato, S. N. Khanna
Physics Publications
The fast-flow tube reaction apparatus was employed to study the halogenation of aluminum clusters. For reactions with HX (X=Cl, Br, and I), acid-etching pathways are evident, and we present findings for several reactions, whereby AlnX− generation is energetically favorable. Tandem reaction experiments allowed us to establish that for AlnCl−, AlnI−, and AlnI−2, species with n=6, 7, and 15 are particularly resistant to attack by oxygen. Further, trends in reactivity suggest that, in general, iodine incorporation leaves the aluminum clusters’ electronic properties largely unperturbed. Ab initio calculations were performed to better interpret reaction mechanisms and elucidate the characteristics of the products. …
Magnetic Properties Of Al, V, Mn, And Ru Impurities In Fe–Co Alloys, B. V. Reddy, S. C. Deevi, S. N. Khanna
Magnetic Properties Of Al, V, Mn, And Ru Impurities In Fe–Co Alloys, B. V. Reddy, S. C. Deevi, S. N. Khanna
Physics Publications
Theoretical studies on the magnetic properties of impurities in Fe–Co alloys have been carried out using a molecular-orbital approach within a gradient corrected density functional formalism. The defected alloy is modeled by a large cluster and the calculations on the ordered alloy are used to show that a cluster containing 67 atoms can provide quantitative information on the local magnetic moment. It is found that although bulk Al, V, and Ru are nonmagnetic, all the impurities carry finite moments. While Al and V impurities couple antiferromagnetically, Ru impurities couple ferromagnetically to the host sites. It is shown that the observed …
H-Substituted Anionic Carbon Clusters Cnh- (N <= 10): Density Functional Studies And Experimental Observations, L. Pan, B. K. Rao, A. K. Gupta, G. P. Das, P. Ayyub
H-Substituted Anionic Carbon Clusters Cnh- (N <= 10): Density Functional Studies And Experimental Observations, L. Pan, B. K. Rao, A. K. Gupta, G. P. Das, P. Ayyub
Physics Publications
We have studied the interaction of hydrogen with small neutral and anionic carbon clusters using density functional calculations. The geometry, stability, and electronic structure of these clusters show an odd–even alternation originating in the bonding nature of the carbon atoms. Our mass spectrometric measurements of the abundance of CnH− (n⩽10) cluster anions produced by gas-feed Cs sputtering from different crystallographic forms of carbon display similar odd–even alternation with the even-n clusters being relatively more abundant. The calculated trend in the adiabatic electron affinities shows a behavior similar to the experimental abundance pattern. We discuss a possible partial suppression of …
Alkalization Of Aluminum Clusters, B. K. Rao, P. Jena
Alkalization Of Aluminum Clusters, B. K. Rao, P. Jena
Physics Publications
Equilibrium geometries, binding energies, ionization potentials, and electron affinities of neutral and charged Aln clusters (n⩽8) decorated with alkali atoms such as Li and K have been calculated using molecular orbital theory based on density functional formalism and generalized gradient approximation. While the electron affinities and the ionization potentials depend on size, no clear signatures of shell closings are found in this size range. Similar studies on Al5Xm (X=Li, K, 1⩽m⩽4) also fail to provide any indication consistent with shell closings. On the other hand, the ionization potentials and electron affinities of aluminum clusters decrease with the addition of alkali …
Experimental And Theoretical Study Of The Photoelectron Spectra Of Mnox-(X=1-3) Clusters, Gennady L. Gutsev, B. K. Rao, P. Jena, Xi Li, Lai-Sheng Wang
Experimental And Theoretical Study Of The Photoelectron Spectra Of Mnox-(X=1-3) Clusters, Gennady L. Gutsev, B. K. Rao, P. Jena, Xi Li, Lai-Sheng Wang
Physics Publications
We report a combined experimental and theoretical investigation of MnO−x and MnOx(x=1–3) clusters. Theoretically, geometrical configurations of various isomers of the clusters were optimized and vertical detachment energies for the anions were evaluated. The ground state of MnO− was predicted to be 5Σ+, followed by an excited state (7Σ+) 0.14 eV higher in energy. The ground state of MnO−2 is 5B2, with a 3B1 isomer 0.15 eV higher. MnO−3 is predicted to be a singlet D3h cluster. Vibrationally resolved photoelectron spectra of MnO−x were measured at several photon energies and under various experimental conditions, and were interpreted based on the …