3,759 research outputs found
Ordered ground states of metallic hydrogen and deuterium
The physical attributes of some of the more physically distinct ordered states of metallic hydrogen and metallic deuterium at T = 0 and nearby are discussed. The likelihood of superconductivity in both is considered with respect to the usual coupling via the density fluctuations of the ions
Astrophysical materials science: Theory
A method of structural expansions for use in determining the equation of state of metallic hydrogen (and indeed other metals) up to the 4th order in the perturbation theory was developed. The electrical and thermal transport properties of the planetary interior of Jupiter were calculated. The nature of the interaction between molecules at short range and the importance of multicenter terms in arriving at an adequate description of the thermodynamic functions of condensed molecular hydrogen were also investigated
Thermal conduction in molecular chains: Non-Markovian effects
We study the effect of non-Markovian reservoirs on the heat conduction
properties of short to intermediate size molecular chains. Using classical
molecular dynamics simulations, we show that the distance dependence of the
heat current is determined not only by the molecular properties, rather it is
also critically influenced by the spectral properties of the heat baths for
both harmonic and anharmonic molecular chains. For highly correlated reservoirs
the current of an anharmonic chain may exceed the flux of the corresponding
harmonic system. Our numerical results are accompanied by a simple single-mode
heat conduction model that can capture the intricate distance dependence
obtained numerically
Excitons with anisotropic effective mass
We present a simple analytic scheme for calculating the binding energy of excitons in semiconductors that takes full account of the existing anisotropy in the effective mass, as a complement to the qualitative treatment in most textbooks. Results obtained for excitons in gallium nitride form the basis for a discussion of the accuracy of this approach
Lyddane-Sachs-Teller relationship in linear magnetoelectrics
In a linear magnetoelectric the lattice is coupled to electric and magnetic
fields: both affect the longitudinal-transverse splitting of zone-center
optical phonons on equal footing. A response matrix relates the macroscopic
fields (D,B) to (E,H) at infrared frequencies. It is shown that the response
matrices at frequencies 0 and \infty fulfill a generalized Lyddane-Sachs-Teller
relationship. The rhs member of such relationship is expressed in terms of
weighted averages over the longitudinal and transverse excitations of the
medium, and assumes a simple form for an harmonic crystal.Comment: 4 pages, no figur
Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter
We show for the first time that the quenching of electronic excitation from
nuclear recoils in liquid xenon is well-described by Lindhard theory, if the
nuclear recoil energy is reconstructed using the combined (scintillation and
ionization) energy scale proposed by Shutt {\it et al.}. We argue for the
adoption of this perspective in favor of the existing preference for
reconstructing nuclear recoil energy solely from primary scintillation. We show
that signal partitioning into scintillation and ionization is well-described by
the Thomas-Imel box model. We discuss the implications for liquid xenon
detectors aimed at the direct detection of dark matter
Observability of a projected new state of matter: a metallic superfluid
Dissipationless quantum states, such as superconductivity and superfluidity,
have attracted interest for almost a century. A variety of systems exhibit
these macroscopic quantum phenomena, ranging from superconducting electrons in
metals to superfluid liquids, atomic vapours, and even large nuclei. It was
recently suggested that liquid metallic hydrogen could form two new unusual
dissipationless quantum states, namely the metallic superfluid and the
superconducting superfluid. Liquid metallic hydrogen is projected to occur only
at an extremely high pressure of about 400 GPa, while pressures on hydrogen of
320 GPa having already been reported. The issue to be adressed is if this state
could be experimentally observable in principle. We propose four experimental
probes for detecting it.Comment: in print in Phys. Rev. Let
Extending Linear Response: Inferences from Electron-Ion Structure Factors
Linear response methods applied to electron systems often display a level of
accuracy which is notable when viewed in terms of the strengths of perturbing
interactions. Neglect of higher response terms is in fact justifiable in many
cases and it can be shown to stem from an intrinsic interference between atomic
and electronic length scales. For fluid metallic systems it can be further
shown that electron-ion structure (increasingly accessible experimentally) can
be understood from an application of linear response in the electron system,
combined with hard-sphere like correlation for the ionic component.Comment: 5 pages, 2 figure
Wigner Crystallization in inhomogeneous one dimensional wires
We explore the theory of electrons confined by one dimensional power law
potentials. We calculate the density profile in the high density electron gas,
the low density Wigner crystal, and the intermediate regime. We extract the
momentum space wavefunction of the electron at the Fermi surface, which can be
measured in experiments on tunneling between parallel wires. The onset of
localization leads to a dramatic broadening of the momentum space wavefunction
together with pronounced sharpening (in energy) of the tunneling spectrum.Comment: 11 pages, 10 figures, RevTeX4: v2. Revised+Expande
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