Showing papers in "Physical Review Letters in 1984"
TL;DR: In this article, a time-dependent version of density functional theory was proposed to deal with the non-perturbative quantum mechanical description of interacting many-body systems moving in a very strong timedependent external field.
Abstract: The response of an interacting many-particle system to a time-dependent external field can usually be treated within linear response theory. Due to rapid experimental progress in the field of laser physics, however, ultra-short laser pulses of very high intensity have become available in recent years. The electric field produced in such pulses can reach the strength of the electric field caused by atomic nuclei. If an atomic system is placed in the focus of such a laser pulse one observes a wealth of new phenomena [1] which cannot be explained by traditional perturbation theory. The non-perturbative quantum mechanical description of interacting particles moving in a very strong time-dependent external field therefore has become a prominent problem of theoretical physics. In principle, it requires a full solution of the time-dependent Schrodinger equation for the interacting many-body system, which is an exceedingly difficult task. In view of the success of density functional methods in the treatment of stationary many-body systems and in view of their numerical simplicity, a time-dependent version of density functional theory appears highly desirable, both within and beyond the regime of linear response.
6,874 citations
TL;DR: In this article, a metallic solid with long-range orientational order, but with icosahedral point group symmetry, which is inconsistent with lattice translations, was observed and its diffraction spots are as sharp as those of crystals but cannot be indexed to any Bravais lattice.
Abstract: We have observed a metallic solid (Al-14-at.%-Mn) with long-range orientational order, but with icosahedral point group symmetry, which is inconsistent with lattice translations. Its diffraction spots are as sharp as those of crystals but cannot be indexed to any Bravais lattice. The solid is metastable and forms from the melt by a first-order transition.
5,702 citations
TL;DR: In this paper, the minimal base of muffin-tin orbitals is transformed exactly into a tight-binding base and the linear transformations, the orbitals, and the Hamiltonian overlap are expressed in terms of one matrix, the canonical structure matrix.
Abstract: The minimal base of muffin-tin orbitals is transformed exactly into a tight-binding base. The linear transformations, the orbitals, and the Hamiltonian, overlap, and Green's function matrices are expressed in terms of one matrix, the canonical structure matrix ${S}_{\mathrm{ij}}$. It vanishes beyond second-nearest neighbors and is tabulated. Tight-binding two-center forms with transfer integrals proportional to ${S}_{\mathrm{ij}}$ are derived.
2,134 citations
TL;DR: In this article, it was found that the level fluctuations of the quantum Sinai's billiard are consistent with the predictions of the Gaussian orthogonal ensemble of random matrices.
Abstract: It is found that the level fluctuations of the quantum Sinai's billiard are consistent with the predictions of the Gaussian orthogonal ensemble of random matrices. This reinforces the belief that level fluctuation laws are universal.
2,004 citations
TL;DR: In this paper, a mass spectra for sodium clusters of $N$ atoms per cluster, produced in a supersonic expansion with argon carrier gas, is presented. The spectra show large peaks or steps at $N=8, 20, 40, 58, \mathrm{and} 92$.
Abstract: Mass spectra are presented for sodium clusters of $N$ atoms per cluster ($N=4\ensuremath{-}100$) produced in a supersonic expansion with argon carrier gas. The spectra show large peaks or steps at $N=8, 20, 40, 58, \mathrm{and} 92$. These can be understood in terms of a one-electron shell model in which independent delocalized atomic $3s$ electrons are bound in a spherically symmetric potential well.
1,909 citations
TL;DR: In this article, the authors present theory and extended experimental results for the large shift in optical absorption in GaAs-AlGaAs quantum well structures with electric field perpendicular to the layers.
Abstract: We present theory and extended experimental results for the large shift in optical absorption in GaAs-AlGaAs quantum well structures with electric field perpendicular to the layers. In contrast to the Stark effect on atoms or on excitons in bulk semiconductors, the exciton resonances remain resolved even for shifts much larger than the zero-field binding energy and fields g 50 times the classical ionization field. The model explains these results as a consequence of the quantum confinement of carriers.
1,604 citations
TL;DR: In this article, two-and three-dimensional quasicrystals were classified by their symmetry under rotation and showed that many disallowed crystal symmetries are allowed quasici-rystal symmets.
Abstract: A quasicrystal is the natural extension of the notion of a crystal to structures with quasiperiodic, rather than periodic, translational order. We classify two- and three-dimensional quasicrystals by their symmetry under rotation and show that many disallowed crystal symmetries are allowed quasicrystal symmetries. We analytically compute the diffraction pattern of an ideal quasicrystal and show that the recently observed electron diffraction pattern of an Al-Mn alloy is closely related to that of an icosahedral quasicrystal.
1,596 citations
TL;DR: A condensed-matter analog of (2+1)-dimensional electrodynamics is constructed in this article, and the consequences of a recently discovered anomaly in such systems are discussed in detail.
Abstract: A condensed-matter analog of (2+1)-dimensional electrodynamics is constructed, and the consequences of a recently discovered anomaly in such systems are discussed.
1,573 citations
TL;DR: In this article, it was shown that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems and are related to energy splittings, which may be observable in real systems.
Abstract: Generalizing a construction of Berry and Simon, we show that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems. Characteristics of the gauge fields are related to energy splittings, which may be observable in real systems. Similar phenomena are found for suitable classical systems.
1,432 citations
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TL;DR: A new type of superstring theory is constructed as a chiral combination of the closed D=26 bosonic and D=10 fermionic strings, which is supersymmetric, Lorentz invariant, and free of tachyons.
Abstract: A new type of superstring theory is constructed as a chiral combination of the closed D=26 bosonic and D=10 fermionic strings. The theory is supersymmetric, Lorentz invariant, and free of tachyons. Consistency requires the gauge group to be Spin(32)Z2 or E8×E8.
1,420 citations
TL;DR: In this paper, a class of models for relaxation in strongly interacting glassy materials is suggested, where degrees of freedom are divided into a sequence of levels such that those in level $n+1$ are locked except when some of those inlevel $n$ find the right combination to release them, representing the hierarchy of constraints in real systems.
Abstract: A class of models for relaxation in strongly interacting glassy materials is suggested. Degrees of freedom are divided into a sequence of levels such that those in level $n+1$ are locked except when some of those in level $n$ find the right combination to release them, this representing the hierarchy of constraints in real systems. The Kohlrausch anomalous relaxation law, $\mathrm{exp}[\ensuremath{-}{(\frac{t}{\ensuremath{\tau}})}^{\ensuremath{\beta}}]$, emerges naturally, and a maximum time scale is found which exhibits a Vogel-Fulcher-type temperature dependence.
TL;DR: In this article, it was shown that the simplest nontrivial stochastic model for dielectric breakdown naturally leads to fractal structures for the discharge pattern, and the results were compared with properly designed experiments.
Abstract: It is shown that the simplest nontrivial stochastic model for dielectric breakdown naturally leads to fractal structures for the discharge pattern. Planar discharges are studied in detail and the results are compared with properly designed experiments.
TL;DR: In this paper, the Schottky barrier heights for metal-semiconductor interfaces with a variety of metals have been calculated, and they are in excellent agreement with experiment for interfaces with various metals.
Abstract: Simple physical considerations of local charge neutrality suggest that near a metal-semiconductor interface, the Fermi level in the semiconductor is pinned near an effective gap center, which is simply related to the bulk semiconductor band structure. In this way “canonical” Schottky barrier heights are calculated for several semiconductors. These are in excellent agreement with experiment for interfaces with a variety of metals.
TL;DR: In this article, it was shown that certain unstable periodic orbits permanently scar some quantum eigenfunctions, in the sense that extra density surrounds the region of the periodic orbit. But this is not the case for all periodic orbits.
Abstract: Certain unstable periodic orbits are shown to permanently scar some quantum eigenfunctions as $\ensuremath{\hbar}\ensuremath{\rightarrow}0$, in the sense that extra density surrounds the region of the periodic orbit.
TL;DR: In this article, the authors show that conformal invariance and unitarity severely limit the possible values of critical exponents in two-dimensional systems, and propose a solution to this problem.
Abstract: Conformal invariance and unitarity severely limit the possible values of critical exponents in two-dimensional systems.
TL;DR: In this article, the effective Lagrangian was derived to describe the interaction between a charged particle and a magnetic moment in the nonrelativistic limit, and it was shown that neutral particles with a magnetic moments will exhibit the Aharonov-Bohm effect in certain circumstances.
Abstract: We derive the effective Lagrangian which describes the interaction between a charged particle and a magnetic moment in the nonrelativistic limit. It is shown that neutral particles with a magnetic moment will exhibit the Aharonov-Bohm effect in certain circumstances. We suggest several types of experiments.
TL;DR: Quasiparticles at the fractional quantized Hall states obey quantization rules appropriate to particles of fractional statistics Stable states at various rational filling factors may be constructed iteratively by adding quasip particles or holes to lower-order states, and the corresponding energies have been estimated.
Abstract: Quasiparticles at the fractional quantized Hall states obey quantization rules appropriate to particles of fractional statistics Stable states at various rational filling factors may be constructed iteratively by adding quasiparticles or holes to lower-order states, and the corresponding energies have been estimated
TL;DR: In this paper, the statistics of quasiparticles entering the quantum Hall effect were deduced from the adiabatic theorem, and these excitations were found to obey fractional statistics, a result closely related to their fractional charge.
Abstract: The statistics of quasiparticles entering the quantum Hall effect are deduced from the adiabatic theorem. These excitations are found to obey fractional statistics, a result closely related to their fractional charge.
TL;DR: In this article, the outer part of the small-angle x-ray or neutron scattering curve for porous scatterers in which the pore boundaries can be described by fractals was analyzed.
Abstract: A method is developed for analyzing the outer part of the small-angle x-ray or neutron scattering curve for porous scatterers in which the pore boundaries can be described by fractals. When the results are applied to the scattering data from a lignite coal, the fractal dimension of the boundary surface of the pores in this coal is found to be 2.56 \ifmmode\pm\else\textpm\fi{}0.03.
TL;DR: In this article, the authors used transmission-electron micrographs to study the structure formed by the irreversible kinetic aggregation of uniformly sized aqueous gold colloids and found that the structures are highly ramified and exhibit a scale invariance that is well described as a fractal with a Hausdorff dimension of 1.75.
Abstract: We use transmission-electron micrographs to study the structure formed by the irreversible kinetic aggregation of uniformly sized aqueous gold colloids. The structures are highly ramified and exhibit a scale invariance that is well described as a fractal with a Hausdorff dimension of \ensuremath{\sim} 1.75. This value is in excellent agreement with recent computer simulations of diffusion-limited aggregation when the clusters themselves are allowed to aggregate.
TL;DR: In this paper, a frequency regime in which electromagnetic waves in a strongly disordered medium undergo Anderson localization in 3D dimensions is suggested, where the renormalized energy absorption coefficient increases as the photon frequency approaches a mobility edge from the conducting side.
Abstract: A frequency regime in which electromagnetic waves in a strongly disordered medium undergo Anderson localization in $d=3$ dimensions is suggested. In the presence of weak dissipation in $d=2+\ensuremath{\epsilon}$ it is shown that the renormalized energy absorption coefficient increases as the photon frequency $\ensuremath{\omega}$ approaches a mobility edge ${\ensuremath{\omega}}^{*}$ from the conducting side as $\ensuremath{\alpha}\ensuremath{\sim}{({\ensuremath{\omega}}^{*}\ensuremath{-}\ensuremath{\omega})}^{\ensuremath{-}\frac{(d\ensuremath{-}2)\ensuremath{
u}}{2}}$, $\ensuremath{
u}=\frac{1}{\ensuremath{\epsilon}}$. This mobility edge occurs at a frequency compatible with the Ioffe-Regel condition.
PARC1
TL;DR: In this paper, the authors compared the band gap between band-and cluster-theory predictions on a cleaved NiO single crystal and showed that a large Coulomb interaction alone does not prevent NiO from being a metal.
Abstract: Photoemission and bremsstrahlung-isochromat-spectroscopy data on a cleaved NiO single crystal are presented and compared to band- and cluster-theory predictions. In contrast to band-theory predictions the band gap is found to be large but not determined solely by the even larger $d\ensuremath{-}d$ Coulomb interactions so that NiO is not a Mott-Hubbard insulator in the simplest sense. A large $d\ensuremath{-}d$ interaction need not prevent NiS from being a metal.
IBM1
TL;DR: A series of twenty homogeneous mixed crystals has been measured dielectrically between 4.2 and 300 K in the tetragonal phase, and the dielectric constant perpendicular to the $c$ axis becomes peaked above ${x}_{c} = 0.0018, the quantum mechanical onset for displacive ferroelectricity as mentioned in this paper.
Abstract: A series of twenty homogeneous ${\mathrm{Sr}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}\mathrm{Ti}{\mathrm{O}}_{3}$ mixed crystals has been measured dielectrically between 4.2 and 300 K. In the tetragonal phase, the dielectric constant perpendicular to the $c$ axis becomes peaked above ${x}_{c}=0.0018$, the quantum mechanical onset for displacive ferroelectricity. The polarization $\ensuremath{\perp}c$ can be switched between the two equivalent $a$ axes, i.e., the system is an $\mathrm{XY}$, $n=2$, quantum ferroelectric. Above ${x}_{r}=0.016\ifmmode\pm\else\textpm\fi{}0.002$, the $\ensuremath{\epsilon}(T)$ peaks round in a distinct manner which we attribute to the onset of a random-field-induced domain state.
TL;DR: In this article, the fractal dimension of colloidal aggregates of small silica particles is measured by both light and x-ray scattering, showing that the aggregates are fractal.
Abstract: Measurement of the fractal dimension, $D$, of colloidal aggregates of small silica particles is reported. We observe power-law decay of the structure factor $[S(k)\ensuremath{\sim}{k}^{\ensuremath{-}D}]$ by both light and x-ray scattering showing that the aggregates are fractal. $D$ is found to be 2.12\ifmmode\pm\else\textpm\fi{}0.05, which is intermediate between recent numerical results for the kinetic models of diffusion-limited aggregation ($D=2.5$) and cluster aggregation ($D=1.75$), but is rather close to the value for lattice animals ($D=2.0$), which are equilibrium structures.
TL;DR: In this article, the authors studied resistance fluctuation in submicrometer narrow Si inversion layers over a wide range of temperatures and electron concentrations, caused by the capture and emission of individual electrons at strategically located scatterers (interface traps).
Abstract: Resistance fluctations in submicrometer narrow Si inversion layers are studied over a wide range of temperatures and electron concentrations. Thermally activated switching on and off of discrete resistance increments is observed, caused by the capture and emission of individual electrons at strategically located scatterers (interface traps). The traps have a broad distribution of activation energies, as assumed in accounting for $\frac{1}{f}$ noise in larger devices.
TL;DR: In this article, Planar as well as spherical targets were irradiated for the first time by the random-phased wave and the targets were uniformly accelerated without being affected by small-scale intensity nonuniformities.
Abstract: By converting a coherent wave to a random-phased wave, the intensity profile on a target becomes easily controllable. Planar as well as spherical targets were irradiated for the first time by the random-phased wave. The targets were uniformly accelerated without being affected by the small-scale intensity nonuniformities. The $\frac{3}{2}$-harmonic emission shows that the plasma waves at $\frac{{n}_{c}}{4}$ are only weakly excited in a spherical plasma. Irradiation with short-wavelength, random-phased beams will be suitable for compression.
TL;DR: In this article, the effective field action due to an odd number of fermion species in three-dimensional SU(N) gauge theories is shown to change by using a homotopically nontrivial gauge transformation with winding number $n.
Abstract: The effective gauge field action due to an odd number of fermion species in three-dimensional $\mathrm{SU}(N)$ gauge theories is shown to change by $\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi}|n|$ under a homotopically nontrivial gauge transformation with winding number $n$. Gauge invariance can be restored by use of Pauli-Villars regularization, which, however, introduces parity nonconservation in the form of a parity-nonconserving, topological term in the effective action.
TL;DR: In this article, it was shown that UPt3 is a spin-fluctuation system and if true, this is the first coexistent superconductor-spinfluctuated system.
Abstract: Convincing evidence has been discovered for bulk superconductivity in UPt3 at 0.54 K based on specific-heat, resistance, and ac susceptibility measurements. In addition, new evidence is presented that indicates that UPt3 is a spin-fluctuation system. If true, this is the first coexistent superconductor-spin-fluctuation system.
TL;DR: In this article, it was suggested that under suitable conditions the propagation of femtosecond optical pulses in electro-optic materials should be accompanied by the radiation of an extremely fast electromagnetic transient, which produces a Cerenkov cone of pulsed radiation having a duration of approximately one cycle and a frequency in the THz range.
Abstract: It was recently suggested that under suitable conditions the propagation of femtosecond optical pulses in electro-optic materials should be accompanied by the radiation of an extremely fast electromagnetic transient [1,2]. This phenomenon, which arises from the inverse electro-optic effect [3], produces a Cerenkov cone of pulsed radiation having a duration of approximately one cycle and a frequency in the THz range.
TL;DR: In this paper, a graph theory of single spin-flip kinetic Ising models is developed and applied to a class of spin models with strongly cooperative dynamics, and self-consistent approximations for the spin time correlation function are presented.
Abstract: A graph theory of single-spin-flip kinetic Ising models is developed and applied to a class of spin models with strongly cooperative dynamics. Self-consistent approximations for the spin time correlation function are presented. One of the dynamical models exhibits a glass transition with no underlying thermodynamic singularity. The approximation for the time correlation function predicts a critical temperature, below which small fluctuations from equilibrium in the thermodynamic limit cannot relax in a finite amount of time.