Showing papers by "John B. Pendry published in 1969"
TL;DR: In this article, the Boudreaux-Heine method of calculating low-energy electron diffraction (LEED) intensities into a matrix form suitable for extension to complicated surface structures is presented.
Abstract: The second paper in this series casts the Boudreaux-Heine method of calculating low-energy electron diffraction (LEED) intensities into a matrix form suitable for extension to complicated surface structures. Calculations are made for the 00 and 01, macron beams reflected from a nickel 111 surface, for norrmal incidence, using the potential described in paper I. Predicted peak positions agree with experiment within ±2 ev and relative intensities agree qualitatively. We interpret our results in terms of band structure. A second calculation for the same face of a nickel crystal with the surface layer displaced by 5% of the bulk spacing between layers is presented, the results of which are interpreted in terms of the large ratio between forward and backward scattering cross section of atoms.
57 citations
TL;DR: In this paper, the consequences of absorbing low-energy electrons from a band structure point of view were discussed from the perspective of band structure and the effect of elastic scattering on low energy electrons.
Abstract: The consequences of absorptive processes for low-energy electrons are discussed from a band structure point of view. By introducing sufficient absorption as an imaginary component of the potential, calculated widths of peaks in the diffraction intensities are fitted to experiment, yielding an estimate for the inelastic intensity-extinction distance of 6 A at E = 70 ev in nickel. Such strong absorption, together with the nature of the elastic scattering, tends to confine flux in the crystal to a narrow cone about the incident beam, making feasible an accurate approximate scheme of calculation which constitutes a considerable simplification on present, formally exact, schemes.
49 citations
TL;DR: In this paper, it was shown that the pseudopotentials of Ziman and Johnson and Slater's augmented plane-wave potential are members of a much larger class of pseudopotential, and a set of rules were proposed for the best choice of radius R, a matter which is especially important at energies above 1-2 ryd such as are used in low-energy electron diffraction.
Abstract: This paper shows that the pseudopotentials of Ziman and Johnson, and Slater's augmented plane-wave potential, are members of a much larger class of pseudopotentials, and proceeds to provide criteria for choosing the pseudopotential most suitable in a given situation. In particular, once the phase shifts have been calculated for the real potential, the radius R in these pseudopotentials is a disposable parameter. A set of rules is proposed for the best choice of R, a matter which is especially important at energies above 1-2 ryd such as are used in low-energy electron diffraction (LEED). One member of this enlarged class of pseudopotentials combines the good convergence properties of the Slater form with the advantage of an angular momentum summation extending over only those values for which the phase shift is non-zero. The convergence, behaviour and misbehaviour, anticipated on theoretical grounds, are demonstrated by numerical calculations.
22 citations
16 citations