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Stable nonlinear heavy-mass impurity modes

1997; American Physical Society; Volume: 55; Issue: 21 Linguagem: Inglês

10.1103/physrevb.55.14265

1095-3795

Yuri S. Kivshar, Fei Zhang, A. S. Kovalev,

Laser-Matter Interactions and Applications

We demonstrate that stable nonlinear localized modes can exist not only at a light-mass isotopic impurity, but also at a heavy-mass impurity, due to an interplay between discreteness and nonlinearity. This is in sharp contrast to the theory of linear lattice vibrations that an impurity mode is possible only at a light-mass defect. We determine the structure of the nonlinear impurity modes analytically using a four-particle approximation, and confirm the stability by direct numerical simulations.