Showing papers by "John B. Pendry published in 1992"
TL;DR: A new methodology enables the band structure and, for the first time, transmission coefficients of complex dielectric materials to be calculated and excellent agreement with experiment is found.
Abstract: The current generation of photon scattering experiments requires a fast, accurate, general technique for calculation of transmission coefficients and of photonic band structure. A new methodology, which has significant advantages of speed and convenience, enables the band structure and, for the first time, transmission coefficients of complex dielectric materials to be calculated. Excellent agreement with experiment is found.
614 citations
TL;DR: The maximal fluctuation theorem as discussed by the authors holds for a wide variety of systems, in one, two and three dimensions, and it is shown by numerical simulations that these coefficients are either O 0 or / 1.
Abstract: the medium. We apply this result to trace(T TL)M, where TL is the amplitude transmission matrix. The eigenfunctions of TL T define a set of channels through which the current flows, and the eigenvalues are the corresponding transmission coefficients. We prove that these coefficients are either O 0 or / 1. As L increases more channels are shut down. This is the maximal fluctuation theorem: fluctuations cannot be greater than this. We expect that our classification scheme will prove of further value in proving theorems about limiting distributions. We show by numerical simulations that our theorem holds good for a wide variety of systems, in one, two and three dimensions. Disordered media scatter waves incident upon them, and induce in the scattered wavefield a degree of disorder which is far more extreme than the physical disorder of the medium itself. The fluctuations are brought about by multiple scattering of the wavefield and its ability to interfere constructively or destructively with itself. The most extreme instances are found in the absence of absorption, when multiple scattering can have free rein. As a specific example we consider the system shown in figure 1 in which waves are incident on a slab of disordered material of finite thickness in one direction, but effectively infinite in the other directions. We shall assume that the slab is statistically homogeneous. The waves can be either transmitted through or reflected from the slab. Statistics in the transmission coefficient pose particular challenges: as the thickness, L, of the slab is increased fluctuations in the transmission coefficient, far from settling down to some 'average' value, become more extreme. The question is what can we say about the limiting scattering properties of a thick slab of material ? As far as we are aware this question has only been addressed for special cases. The results we derive here apply in very general circumstances,
106 citations
TL;DR: In this article, a new LEED study of the clean and hydrogen induced c(2×2) reconstruction of W(100) was presented, which showed that the LEED intensity analysis for data taken at sufficiently oblique incidence (θ≈74°) provides high sensitivity for surface parallel parameters without loosing that for coordinates normal to the surface.
32 citations
TL;DR: In this paper, low energy electron diffraction (LEED) was used to investigate the adaption of potassium on a nickel (100)-substrate and a well ordered c(4 × 2) superstructure was observed which is stable up to temperatures of about 200 K.
29 citations
TL;DR: A linear approximation to dynamical low-energy electron diffraction (LEED) is proposed, called linear LEED (LLEED), which may hold the key to the solution of complex surface structures with large atomic displacements, in a way complementary to tensor LEED.
Abstract: A linear approximation to dynamical low-energy electron diffraction (LEED) is proposed, called linear LEED (LLEED). It may hold the key to the solution of complex surface structures with large atomic displacements, in a way complementary to tensor LEED. More ambitious possibilities also present themselves, based on direct inversion schemes and related in spirit to holographic ideas. Linear LEED relies on the approximate linear independence of diffracted amplitudes from subunits such as atoms or molecules, and reduces enormously the number of full dynamical LEED calculations needed in a structural search.
19 citations
TL;DR: The recent suggestion that a diffuse low-energy-electron-diffraction pattern from a disordered layer of adsorbate atoms on a crystal surface may be interpreted as a Fraunhofer hologram is put to a practical test in the case of O/Ni(100).
Abstract: The recent suggestion that a diffuse low-energy-electron-diffraction pattern from a disordered layer of adsorbate atoms on a crystal surface may be interpreted as a Fraunhofer hologram, from which crystallographic information may be extracted directly, is put to a practical test in the case of O/Ni(100). Holographic reconstruction yields an image of the Ni atoms closest to the O adsorbates. The image resolution appears sufficient for its use as a starting point for more established crystallographic techniques, to discriminate, in a preliminary search, between very different models
14 citations
TL;DR: In this paper, the coefficients of such a power series expansion can be derived from the first-order Tensor-LEED approximation by evaluating simple recurrence relations, and a new way of shifting the origin of coordinates by using the full second-order tensor-leed approximation is developed.
9 citations
TL;DR: In this paper, new ways of interpreting diffraction data are explored with a view to extending the power and flexibility of tools available to us for determining surface crystallography, such is the demand for structural information at surfaces.
Abstract: Electrons are the main probe for determining surface crystallography Existing methods have already established an impresive list of completed structures but, such is the demand for structural information at surfaces, new ways of interpreting diffraction data are being explored with a view to extending the power and flexibility of tools available to us
2 citations
TL;DR: In this paper, a flexible method for calculating the conductance coefficients of small multi-terminal devices, in terms of real space Green functions (GFs) in a discretized space, is presented.