39,125 research outputs found
Structure and electronic properties of molybdenum monoatomic wires encapsulated in carbon nanotubes
Monoatomic chains of molybdenum encapsulated in single walled carbon
nanotubes of different chiralities are investigated using density functional
theory. We determine the optimal size of the carbon nanotube for encapsulating
a single atomic wire, as well as the most stable atomic arrangement adopted by
the wire. We also study the transport properties in the ballistic regime by
computing the transmission coefficients and tracing them back to electronic
conduction channels of the wire and the host. We predict that carbon nanotubes
of appropriate radii encapsulating a Mo wire have metallic behavior, even if
both the nanotube and the wire are insulators. Therefore, encapsulating Mo
wires in CNT is a way to create conductive quasi one-dimensional hybrid
nanostructures.Comment: 8 pages, 10 figure
A model for conservative chaos constructed from multi-component Bose-Einstein condensates with a trap in 2 dimensions
To show a mechanism leading to the breakdown of a particle picture for the
multi-component Bose-Einstein condensates(BECs) with a harmonic trap in high
dimensions, we investigate the corresponding 2- nonlinear Schr{\"o}dinger
equation (Gross-Pitaevskii equation) with use of a modified variational
principle. A molecule of two identical Gaussian wavepackets has two degrees of
freedom(DFs), the separation of center-of-masses and the wavepacket width.
Without the inter-component interaction(ICI) these DFs show independent regular
oscillations with the degenerate eigen-frequencies. The inclusion of ICI
strongly mixes these DFs, generating a fat mode that breaks a particle picture,
which however can be recovered by introducing a time-periodic ICI with zero
average. In case of the molecule of three wavepackets for a three-component
BEC, the increase of amplitude of ICI yields a transition from regular to
chaotic oscillations in the wavepacket breathing.Comment: 5 pages, 4 figure
Non-equilibrium transport response from equilibrium transport theory
We propose a simple scheme that describes accurately essential
non-equilibrium effects in nanoscale electronics devices using equilibrium
transport theory. The scheme, which is based on the alignment and dealignment
of the junction molecular orbitals with the shifted Fermi levels of the
electrodes, simplifies drastically the calculation of current-voltage
characteristics compared to typical non-equilibrium algorithms. We probe that
the scheme captures a number of non-trivial transport phenomena such as the
negative differential resistance and rectification effects. It applies to those
atomic-scale junctions whose relevant states for transport are spatially placed
on the contact atoms or near the electrodes.Comment: 5 pages, 4 figures. Accepted in Physical Review
Impact of dimerization and stretching on the transport properties of molybdenum atomic wires
We study the electrical and transport properties of monoatomic Mo wires with
different structural characteristics. We consider first periodic wires with
inter-atomic distances ranging between the dimerized wire to that formed by
equidistant atoms. We find that the dimerized case has a gap in the electronic
structure which makes it insulating, as opposed to the equidistant or
near-equidistant cases which are metallic. We also simulate two conducting
one-dimensional Mo electrodes separated by a scattering region which contains a
number of dimers between 1 and 6. The characteristics strongly depend on
the number of dimers and vary from ohmic to tunneling, with the presence of
different gaps. We also find that stretched chains are ferromagnetic.Comment: 8 pages, 7 figure
A note on static dyonic diholes
In this brief note we argue that a dyonic generalization of the Emparan-Teo
dihole solution is described by a static diagonal metric and therefore,
contrary to the claim made in a recent paper by Cabrera-Munguia et al., does
not involve any "non-vanishing global angular momentum" and rotating charges.Comment: 4 pages, 1 figure; typos corrected, matches the published versio
- …