2,310 research outputs found
Evidence for a single hydrogen molecule connected by an atomic chain
Stable, single-molecule conducting-bridge configurations are typically
identified from peak structures in a conductance histogram. In previous work on
Pt with H at cryogenic temperatures it has been shown that a peak near 1
identifies a single molecule Pt-H-Pt bridge. The histogram shows
an additional structure with lower conductance that has not been identified.
Here, we show that it is likely due to a hydrogen decorated Pt chain in contact
with the H molecular bridge.Comment: 4 pages, 4 figure
Effect of bonding of a CO molecule on the conductance of atomic metal wires
We have measured the effect of bonding of a CO molecule on the conductance of
Au, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the
metal nano contacts, a conductance feature appears in the conductance histogram
near 0.5 of the quantum unit of conductance, for all metals. For Au, the
intensity of this fractional conductance feature can be tuned with the bias
voltage, and it disappears at high bias voltage (above 200 mV). The
bonding of CO to Au appears to be weakest, and associated with monotomic Au
wire formation.Comment: 6 figure
Total energy calculation of high pressure selenium: The origin of incommensurate modulations in Se-IV and the instability of proposed Se-II
We present calculation of the high pressure crystal structures in selenium,
including rational approximants to the recently reported incommensurate phases.
We show how the incommensurate phases can be intuitively explained in terms of
imaginary phonon frequencies arising from Kohn anomalies in the putative
undistorted phase. We also find inconsistencies between the calculated and
experimental Se-II phase - the calculations show it to be a metastable metal
while the experiment finds a stable semiconductor. We propose that the
experimentally reported structure is probably in error.Comment: 4 pages 4 figure
A Spin-Isospin Dependent 3N Scattering Formalism in a 3D Faddeev Scheme
We have introduced a spin-isospin dependent three-dimensional approach for
formulation of the three-nucleon scattering. Faddeev equation is expressed in
terms of vector Jacobi momenta and spin-isospin quantum numbers of each
nucleon. Our formalism is based on connecting the transition amplitude to
momentum-helicity representations of the two-body -matrix and the deuteron
wave function. Finally the expressions for nucleon-deuteron elastic scattering
and full breakup process amplitudes are presented.Comment: 17 page
Magnetocaloric Properties of the Ni2Mn1−x(Cu,Co)xGa Heusler Alloys
We have investigated the magnetocaloric properties on the Ni2Mn1−xAxGa Heusler alloys with partial substitution of Mn by A = Co (x = 0.10, 0.20, and 0.30) and Cu (x = 0.15 and 0.20) in the vicinity of the martensitic transition by measuring magnetization curves at magnetic field up to 20 kOe and in the temperature range of 250–300 K. The changes of the magnetic part of entropy dependence on magnetic field and temperature have been evaluated
Trapping and ground-state cooling of
We demonstrate co-trapping and sideband cooling of a ion
pair in a cryogenic Paul trap. We study the chemical lifetime of and
its dependence on the apparatus temperature, achieving lifetimes of up to
at 10 K. We demonstrate cooling of translational motion to an
average phonon number of 0.07(1), corresponding to a temperature of . Our results provide a basis for quantum logic spectroscopy experiments of
, as well as other light ions such as , , and
Annealing schedule from population dynamics
We introduce a dynamical annealing schedule for population-based optimization
algorithms with mutation. On the basis of a statistical mechanics formulation
of the population dynamics, the mutation rate adapts to a value maximizing
expected rewards at each time step. Thereby, the mutation rate is eliminated as
a free parameter from the algorithm.Comment: 6 pages RevTeX, 4 figures PostScript; to be published in Phys. Rev.
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