30 research outputs found
Kink plateau dynamics in finite-size lubricant chains
We extend the study of velocity quantization phenomena recently found in the
classical motion of an idealized 1D model solid lubricant -- consisting of a
harmonic chain interposed between two periodic sliding potentials [Phys. Rev.
Lett. 97, 056101 (2006)]. This quantization is due to one slider rigidly
dragging the commensurate lattice of kinks that the chain forms with the other
slider. In this follow-up work we consider finite-size chains rather than
infinite chains. The finite size (i) permits the development of robust velocity
plateaus as a function of the lubricant stiffness, and (ii) allows an overall
chain-length re-adjustment which spontaneously promotes single-particle
periodic oscillations. These periodic oscillations replace the quasi-periodic
motion produced by general incommensurate periods of the sliders and the
lubricant in the infinite-size model. Possible consequences of these results
for some real systems are discussed.Comment: 12 pages, 5 figures, ECOSS 200
Quantum Frenkel-Kontorova Model
This paper gives a review of our recent work on the quantum Frenkel-Kontorova
model. Using the squeezed state theory and the quantum Monte Carlo method, we
have studied the effects of quantum fluctuations on the Aubry transition and
the behavior of the ground state wave function. We found that quantum
fluctuations renormalize the sinusoidal standard map to a sawtooth map.
Although quantum fluctuations have smeared the Aubry transition, the remnants
of this transition are still discernible. The ground state wave function also
changes from an extended state to a localized state. The squeezed state results
agree very well with those from the Monte Carlo and mean field studies.Comment: 20 pages in elsart.sty, 11 eps figure
Action-derived molecular dynamics in the study of rare events
We present a practical method to generate classical trajectories with fixed
initial and final boundary conditions. Our method is based on the minimization
of a suitably defined discretized action. The method finds its most natural
application in the study of rare events. Its capabilities are illustrated by
non-trivial examples. The algorithm lends itself to straightforward
parallelization, and when combined with molecular dynamics (MD) it promises to
offer a powerful tool for the study of chemical reactions.Comment: 7 Pages, 4 Figures (3 in color), submitted to Phys. Rev. Let
Investigating Rare Events by Transition Interface Sampling
We briefly review simulation schemes for the investigation of rare
transitions and we resume the recently introduced Transition Interface
Sampling, a method in which the computation of rate constants is recast into
the computation of fluxes through interfaces dividing the reactant and product
state.Comment: 12 pages, 1 figure, contributed paper to the proceedings of NEXT
2003, Second Sardinian International Conference on News and Expectations in
Thermostatistics, 21-28 Sep 2003, Cagliari (Italy
CHEMICAL PHYSICS LETTERS Electrostatics by Brownian dynamics: solving the Poisson equation near dielectric interfaces
The isomorphism between electrostatics and diffusion is discussed and utilized to develop a Brownian dynamics algorithm for solving the Poisson equation near dielectric interfaces. The electrostatic potential behaves as if carried by noninteracting, randomly moving pseudo-pa~cles whose residence time in a given region of space is proportional to the electrostatic potential there. By applying random numbers from the exact solution for diffusion near a planar discontinuity, the Brownian motion of these particles can be propagated for large time steps, independent of spatial grids or artificial boundary conditions. The applicability of the Brownian algorithm is demonstrated in simple illustrative calculations. © 1997 Elsevier Science B.V. 1