10 research outputs found
A supersonic crowdion in mica: Ultradiscrete kinks with energy between K recoil and transmission sputtering
In this chapter we analyze in detail the behaviour and properties of the
kinks found in an one dimensional model for the close packed rows of potassium
ions in mica muscovite. The model includes realistic potentials obtained from
the physics of the problem, ion bombardment experiments and molecular dynamics
fitted to experiments. These kinks are supersonic and have an unique velocity
and energy. They are ultradiscrete involving the translation of an interstitial
ion, which is the reason they are called 'crowdions'. Their energy is below the
most probable source of energy, the decay of the K isotope and above the
energy needed to eject an atom from the mineral, a phenomenon that has been
observed experimentallyComment: 28 pages, 15 figure
Collective-coordinate analysis of inhomogeneous nonlinear Klein-Gordon field theory
Two different sets of collective-coordinate equations for solitary solutions
of Nonlinear Klein-Gordon (NKG) model is introduced. The collective-coordinate
equations are derived using different approaches for adding the inhomogeneities
as exrernal potentials to the soliton equation of motion. Interaction of the
NKG field with a local inhomogeneity like a delta function potential wall and
also delta function potential well is investigated using the presented
collective-coordinate equations and the results of two different models are
compared. Most of the characters of the interaction are derived analytically.
Analytical results are also compared with the results of numerical simulations.Comment: 16 pages, 8 figures. Accepted for publication in Volume 43 of the
Brazilian Journal of Physic