| Original Articles |
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Two-Dimensional Discrete Gap Breathers in a Two-Dimensional Diatomic β Fermi--Pasta--Ulam Lattice |
| XU Quan1,2, TIAN Qiang2 |
| 1Department of Physics, Daqing Normal University, Daqing 1637122Department of Physics, Beijing Normal University, Beijing 100875 |
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| Cite this article: |
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XU Quan, TIAN Qiang 2008 Chin. Phys. Lett. 25 3586-3589 |
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Abstract We study the existence of two-dimensional discrete breathers in a two-dimensional face-centred square lattice consisting of alternating light and heavy atoms, with nearest-neighbour coupling containing quartic soft or hard
nonlinearity. This study is focused on two-dimensional breathers with frequency in the gap that separates the acoustic and optical bands of the phonon spectrum. We demonstrate the possibility of existence of two-dimensional gap breathers by using the numerical method, the local anharmonicity approximation and the rotating wave approximation. We obtain six types of two-dimensional gap breathers, i.e., symmetric, mirror-symmetric and asymmetric, no matter whether the centre of the breather is on a light or a heavy atom.
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| Keywords:
05.45.Xt
20.30.Jr
63.20.Pw
63.20.Ry
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Received: 13 May 2008
Published: 26 September 2008
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