David K . Campbell

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Using recent results on a model relativistic field theory, we find explicitly a new solitonlike solution, essentially the conventional strong polaron, in the continuum interacting electronphonon model of a Peierls-dimerized chain such as polyacetylene [(CH}„].This solution is in good agreement with recent numerical simulations in a discrete model of (CH)„.(More)
Surface reactions with oxygen are a fundamental cause of the degradation of phosphorene. Using first-principles calculations, we show that for each oxygen atom adsorbed onto phosphorene there is an energy release of about 2 eV. Although the most stable oxygen adsorbed forms are electrically inactive and lead only to minor distortions of the lattice, there(More)
We present analytic and numerical results on several models of one-dimensional (1D) classical lattices with the goal of determining the origins of anomalous heat transport and the conditions for normal transport in these systems. Some of the recent results in the literature are reviewed and several original "toy" models are added that provide key elements(More)
We examine and explain the Luttinger-liquid character of models solvable by the Bethe ansatz by introducing a suitable bosonic operator algebra. In the case of the Hubbard chain, this involves two bosonic algebras which apply to all values of U , electronic density, and magnetization. Only at zero magnetization does this lead to the usual charge spin(More)
We introduce a new operator algebra for the description of the low-energy physics of one-dimensional, integrable, multicomponent quantum liquids. Considering the particular case of the Hubbard chain in a constant external magnetic field and with varying chemical potential, we show that at low energy its Bethe-ansatz solution can be interpreted in terms of(More)
We calculate the phonon spectrum for a graphene sheet resulting from the model proposed by Lenosky et al. Nature London 355, 333 1992 for the free energy of the lattice. This model takes into account not only the usual bond-bending and stretching terms, but it also captures the possible misalignment of the pz orbitals. We compare our results with previous(More)
by David K. Campbell No tribute to the legacy of Stan Ulam would be complete without a discussion of “nonlinear science,” a growing collection of interdisciplinary studies that in the past two decades has excited and challenged researchers from nearly every discipline of the natural sciences, engineering, and mathematics. Through his own research Stan(More)
ally perceived as arising from extrinsic disorder that breaks the discrete translational invariance of the perfect crystal lattice. Familiar examples include the localized vibrational phonon modes around impurities or defects (such as atomic vacancies or interstitial atoms) in crystals and Anderson localization of electrons in disordered media.1 The usual(More)