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G Kopidakis

Publications and source records attributed to G Kopidakis.

5 recordsLinked to original sources
PubMed2001

Targeted energy transfer through discrete breathers in nonlinear systems.

We propose a simple, novel mechanism for inducing highly selective and efficient energy transfer and focusing in certain discrete nonlinear systems. Under a precise condition of nonlinear resonance, when a specific amount of energy is injected as a discrete breather at a donor system, it can be transferred as a discrete breather to another weakly coupled acceptor system. This general mechanism could be relevant for energy transfer in bioenergetics and electron transfer in chemical reactions and could be used for engineering functional materials and devices.

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PubMed2000

Oscillatory instabilities of standing waves in one-dimensional nonlinear lattices.

In one-dimensional anharmonic lattices, we construct nonlinear standing waves (SWs) reducing to harmonic SWs at small amplitude. For SWs with spatial periodicity incommensurate with the lattice period, a transition by breaking of analyticity versus wave amplitude is observed. As a consequence of the discreteness, oscillatory linear instabilities, persisting for arbitrarily small amplitude in infinite lattices, appear for all wave numbers Q not equal 0,pi. Incommensurate analytic SWs with |Q|>pi/2 may however appear as "quasistable," as their instability growth rate is of higher order.

Journal Article↗
PubMed2000

Discrete breathers and delocalization in nonlinear disordered systems

We find exact localized time-periodic solutions with frequencies inside the linearized spectrum [intraband discrete breathers (IDBs)] in random nonlinear models using a new self-consistent method. The IDB frequencies belong to intervals between forbidden gaps generated by resonances with the linear modes, becoming fat Cantor sets in infinite systems. When localized IDBs are continued versus frequency, they delocalize and become multisite IDBs (not predicted by existing theorems), which can propagate energy. Some implications for energy relaxation in glasses are discussed.

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