77 research outputs found
Rearrangement collisions between gold clusters
Collision processes between two gold clusters are investigated using
classical molecular dynamics in combination with embedded atom (EA) potentials,
after checking the reliability of EA results by contrasting them with first
principles calculations. The Au projectiles considered are both single atoms
(N=1) and clusters of N=2, 12, 13 and 14 atoms. The targets contain N= 12, 13
and 14 gold atoms. The initial projectile energy E is in the range 0 < E < 1.5
eV/atom. The results of the collision processes are described and analyzed in
detail.Comment: LATeX file, 8 figures, uses svjour.cl
Nucleation of superfluid-light domains in a quenched dynamics
Strong correlation effects emerge from light-matter interactions in coupled
resonator arrays, such as the Mott-insulator to superfluid phase transition of
atom-photon excitations. We demonstrate that the quenched dynamics of a
finite-sized complex array of coupled resonators induces a first-order like
phase transition. The latter is accompanied by domain nucleation that can be
used to manipulate the photonic transport properties of the emerging superfluid
phase; this in turn leads to an empirical scaling law. This universal behavior
emerges from the light-matter interaction and the topology of the array. The
validity of our results over a wide range of complex architectures might lead
to to a promising device for use in scaled quantum simulations.Comment: 7 pages, 4 figures and supplemental material. Accepted by Scientific
Report
Temperature-dependent properties of 147-and 309-atom iron-gold nanoclusters
The properties of several Au-N and AuN-xFex nanoclusters are obtained by means of classical molecular dynamics calculations. In particular we study the configurations Au-147, Au134Fe13, Au-309, and Au254Fe55, which correspond to icosahedral magic numbers, for both the gold and the iron. We investigate the melting and freezing processes, atomic diffusion, hardness, vibration spectra, and specific heat of these nanoclusters. All the data obtained point toward the stability of the AuN-xFex system, with the gold atoms on the outside of the iron core
Internal Rotation of Disilane and Related Molecules:a Density Functional Study
DFT calculations performed on Si_2H_6, Si_2F_6, Si_2Cl_6, and Si_2Br_6 are
reported. The evolution of the energy, the chemical potential and the molecular
hardness, as a function of torsion angle, is studied. Results at the
DFT-B3LYP/6-311++G** level show that the molecules always favor the stable
staggered conformations, with low but significant energy barriers that hinder
internal rotation. The chemical potential and hardness of Si_2H_6 remains quite
constant as the sylil groups rotate around the Si-Si axis, whereas the other
systems exhibit different degrees of rearrangement of the electronic density as
a function of the torsion angle. A qualitative analysis of the frontier
orbitals shows that the effect of torsional motion on electrophilic attack is
negligible, whereas this internal rotation may generate different specific
mechanisms for nucleophilic attack.Comment: LATeX file, 7 figures, uses elsart.cls, natbib, graphic
Microwave plasma assisted preparation of Pd-nanoparticles with controlled dispersion on woven activated carbon fibres
Electron-phonon coupling in mixed-valence systems
The electron-phonon interaction in mixed-valence systems is modeled on the basis of an Anderson-like Hamiltonian that describes a cluster of one metallic rare-earth cation surrounded by six anions. Coupling between the electronic and phononic variables is introduced, keeping two different phonon modes: a breathing and an asymmetric mode. The first, related to the ionic radius, is treated exactly. The asymmetric mode, which determines the sd-f hybridization, is dealt with in the Born-Oppenheimer approximation. A variety of experimental results are adequately accounted for by this simple model, like the anomalous thermal expansion, the Debye-Waller factor, the phonon softening and broadening, and the charge-distance correlation. © 1991 The American Physical Society
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