Asymmetry Localized Modes in an Anharmonic Sphalerite-Structure Lattice
ZHOU Guang-Hui1,3, XIA Qing-Lin1, PAN Liu-Xian2, YAN Jia-Ren1
1Department of Physics and Institute of Nonlinear Science, Hunan Normal University, Changsha 410081
2Department of Physics, Yiyang Teachers College, Yiyang 413049
3International Center for Materials Physics, Chinese Academy of Sciences, Shenyang 110015
Asymmetry Localized Modes in an Anharmonic Sphalerite-Structure Lattice
1Department of Physics and Institute of Nonlinear Science, Hunan Normal University, Changsha 410081
2Department of Physics, Yiyang Teachers College, Yiyang 413049
3International Center for Materials Physics, Chinese Academy of Sciences, Shenyang 110015
Abstract： We numerically study the intrinsic localized vibrational modes in a diatomic chain with different masses and alternating force constants between nearest neighbors. This model simulates a row of atoms in the <111> direction of sphalerite-structure crystal. We found that the harmonic and quartic anharmonic terms in the nearest-neighbor interaction potential produce the intrinsic localized modes with frequencies above the optical branch or in the gap of the linear spectrum, the distribution patterns of atom amplitudes are asymmetry with a form of quasi-even- or quasi-odd-parity, and the inclusion of cubic term in the potential lowers the frequencies of the modes and introduces static displacements for the atoms.
2000, Vol. 17 
