Showing papers by "Eugene J. Mele published in 1998"

Temperature-dependent resistivity of single-wall carbon nanotubes

Abstract: Samples of single-wall carbon nanotubes containing tubes with an armchair wrapping have been produced and exhibit metallic behavior with an intrinsic resistivity which increases approximately linearly with temperature over a wide temperature range. Here we study the coupling of the conduction electrons to long-wavelength torsional shape fluctuations, or twistons. A one-dimensional theory of the scattering of electrons by twistons is presented which predicts an intrinsic resistivity proportional to the absolute temperature. Experimental measurements of the temperature dependence of the resistivity are reported and compared with the predictions of the twiston theory.

Structure and vibrations of the vicinal copper (211) surface

Abstract: We report a first-principles theoretical study of the surface relaxation and lattice dynamics of the $\mathrm{Cu}(211)$ surface using the plane-wave pseuodopotential method. We find large atomic relaxations for the first several atomic layers near the step edges on this surface, and a substantial step-induced renormalization of the surface harmonic force constants. We use the results to study the harmonic fluctuations around the equilibrium structure and identify three new step-derived features in the zone-center vibrational spectrum. Comparisons of these results with previous theoretical work and with experimental studies using inelastic He-atom scattering are reported.

Continuum elastic theory of adsorbate vibrational relaxation

Abstract: An analytical theory is presented for the damping of low-frequency adsorbate vibrations via resonant coupling to the substrate phonons. The system is treated classically, with the substrate modeled as a semi-infinite elastic continuum and the adsorbate overlayer modeled as an array of point masses connected to the surface by harmonic springs. The theory provides a simple expression for the relaxation rate in terms of fundamental parameters of the system: γ=mω02/AcρcT, where m is the adsorbate mass, ω0 is the measured frequency, Ac is the overlayer unit-cell area, and ρ and cT are the substrate mass density and transverse speed of sound, respectively. This expression is strongly coverage dependent, and predicts relaxation rates in excellent quantitative agreement with available experiments. For a half-monolayer of carbon monoxide on the copper (100) surface, the predicted damping rate of in-plane frustrated translations is 0.50×1012 s−1, as compared to the experimental value of (0.43±0.07)×1012 s−1. Furt...

Collective Motion and Structural Order in Adsorbate Vibrational Dynamics

Abstract: A simple, broadly applicable theory is developed to describe resonant vibrational coupling between adsorbates and a substrate lattice This is one of the principal mechanisms governing the relaxation of adsorbate vibrations This theory can be applied to widely varying surface coverages and arbitrary overlayer structures, and it correctly incorporates collective adsorbate motion, which has been shown to have a critical impact on the relaxation dynamics Vibrational lifetimes predicted by this theory are in excellent quantitative agreement with experiments on adsorbate systems ranging from a diffuse, disordered overlayer to a dense, periodic overlayer {copyright} {ital 1998} {ital The American Physical Society }