218 research outputs found
Interfacial tension behavior of binary and ternary mixtures of partially miscible Lennard-Jones fluids: a molecular dynamics simulation
By means of extensive equilibrium molecular dynamics simulations we have
investigated, the behavior of the interfacial tension of two
immiscible symmetrical Lennard-Jones fluids. This quantity is studied as
function of reduced temperature in the range
. We find that, unlike the monotonic decay obtained
for the liquid-vapor interfacial tension, for the liquid-liquid interface,
has a maximum at a specific temperature. We also investigate the
effect that surfactant-like particles has on the thermodynamic as well as the
structural properties of the liquid-liquid interface. It is found that
decays monotonically as the concentration of the surfactant-like particles
increases.Comment: LaTeX-Revtex file with 7 encapsulated postscript figures. Accepted
for publication in Journal of Chemical Physic
Light trapping and guidance in plasmonic nanocrystals
We illustrate the possibility of light trapping and funneling in periodic
arrays of metallic nanoparticles. A controllable minimum in the transmission
spectra of such constructs arises from a collective plasmon resonance
phenomenon, where an incident plane wave sharply localizes in the vertical
direction, remaining delocalized in the direction parallel to the crystal
plane. Using hybrid arrays of different structures or different materials, we
apply the trapping effect to structure the eigen-mode spectrum, introduce
overlapping resonances, and hence direct the light in space in a
wavelength-sensitive fashion
Disorder induced local density of states oscillations on narrow Ag(111) terraces
The local density of states of Ag(111) has been probed in detail on
disordered terraces of varying width by dI/dV-mapping with a scanning tunneling
microscope at low temperatures. Apparent shifts of the bottom of the
surface-state band edge from terrace induced confinement are observed.
Disordered terraces show interesting contrast reversals in the dI/dV maps as a
function of tip-sample voltage polarity with details that depend on the average
width of the terrace and the particular edge profile. In contrast to perfect
terraces with straight edges, standing wave patterns are observed parallel to
the step edges, i.e. in the non-confined direction. Scattering calculations
based on the Ag(111) surface states reproduce these spatial oscillations and
all the qualitative features of the standing wave patterns, including the
polarity-dependent contrast reversals.Comment: 19 pages, 12 figure
Snell's law for surface electrons: Refraction of an electron gas imaged in real space
On NaCl(100)/Cu(111) an interface state band is observed that descends from
the surface-state band of the clean copper surface. This band exhibits a
Moire-pattern-induced one-dimensional band gap, which is accompanied by strong
standing-wave patterns, as revealed in low-temperature scanning tunneling
microscopy images. At NaCl island step edges, one can directly see the
refraction of these standing waves, which obey Snell's refraction law.Comment: 4 pages, 4 figure
The demixing phase instability in the ion-dipole mixture
By considering the variation of the grand potential functional Ω with respect
to small density fluctuations δρα(1) we can determine the phase instability
of a system from the correlation functions. Using the reference hypernetted
chain (RHNC) approximation the correlation functions of an iondipole
mixture have been calculated. With the obtained correlation functions
the phase behaviour of ion-dipole mixtures has been investigated.Розглядаючи варіацію функціоналу великого потенціалу Ω по відношенню до малих флуктуацій густини δρα (1), ми можемо визначити фазову нестійкість системи з кореляційних функцій. Обчислено кореляційні функції іонно-дипольної суміші, використовуючи базисне гіперланцюгове наближення. На основі отриманих кореляційних функцій була досліджена фазова поведінка іонно-дипольних сумішей
Optical Properties of Crystals with Spatial Dispersion: Josephson Plasma Resonance in Layered Superconductors
We derive the transmission coefficient, , for grazing incidence of
crystals with spatial dispersion accounting for the excitation of multiple
modes with different wave vectors for a given frequency . The
generalization of the Fresnel formulas contains the refraction indices of these
modes as determined by the dielectric function . Near
frequencies , where the group velocity vanishes, depends
also on an additional parameter determined by the crystal microstructure. The
transmission is significantly suppressed, if one of the excited modes is
decaying into the crystal. We derive these features microscopically for the
Josephson plasma resonance in layered superconductors.Comment: 4 pages, 2 figures, epl.cls style file, minor change
Collisionless hydrodynamics for 1D motion of inhomogeneous degenerate electron gases: equivalence of two recent descriptions
Recently I. Tokatly and O. Pankratov (''TP'', Phys. Rev. B 60, 15550 (1999))
used velocity moments of a semiclassical kinetic equation to derive a
hydrodynamic description of electron motion in a degenerate electron gas.
Independently, the present authors (Theochem 501-502, 327 (2000)) used
considerations arising from the Harmonic Potential Theorem (Phys. Rev. Lett.
73, 2244 (1994)) to generate a new form of high-frequency hydrodynamics for
inhomogeneous degenerate electron gases (HPT-N3 hydrodynamics). We show here
that TP hydrodynamics yields HPT-N3 hydrodynamics when linearized about a
Thomas-Fermi groundstate with one-dimensional spatial inhomnogeneity.Comment: 17p
Surface Screening in the Casimir Force
We calculate the corrections to the Casimir force between two metals due to
the spatial dispersion of their response functions. We employ model-independent
expressions for the force in terms of the optical coefficients. We express the
non-local corrections to the Fresnel coefficients employing the surface
parameter, which accounts for the distribution of the surface
screening charge. Within a self-consistent jellium calculation, spatial
dispersion increases the Casimir force significatively for small separations.
The nonlocal correction has the opposite sign than previously predicted
employing hydrodynamic models and assuming abruptly terminated surfaces.Comment: 5 pages, 2 figure
Thomas-Fermi-Dirac-von Weizsacker hydrodynamics in laterally modulated electronic systems
We have studied the collective plasma excitations of a two-dimensional
electron gas with an arbitrary lateral charge-density modulation. The dynamics
is formulated using a previously developed hydrodynamic theory based on the
Thomas-Fermi-Dirac-von Weizsacker approximation. In this approach, both the
equilibrium and dynamical properties of the periodically modulated electron gas
are treated in a consistent fashion. We pay particular attention to the
evolution of the collective excitations as the system undergoes the transition
from the ideal two-dimensional limit to the highly-localized one-dimensional
limit. We also calculate the power absorption in the long-wavelength limit to
illustrate the effect of the modulation on the modes probed by far-infrared
(FIR) transmission spectroscopy.Comment: 27 page Revtex file, 15 Postscript figure
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