Computer Experiments on Propagation of Non-linear Wave in Two-Dimensional Hexagonal Model Crystals

摘要

Molecular dynamics computer experiments have been carried out for two-dimensional hexagonal mass-spring model crystals. Anharmonic forces up to the third order were taken into account, and central forces were considered between the nearest neighbor (nn) and the next nearest neighbor (nnn) atoms. The ratio of the potential between the nnn atoms to the potential between the nn atoms was varied. An input pulse displacement was given to central atomic planes in the crystal or to the end atomic plane of the crystal, and induced displacements and velocities of all atoms were computed. Solitons were produced as the atomic excitation, and the propagation velocity and the strength of solitons were enumerated. Two crystallographic directions were taken for the input pulse direction, and the values of the nnn interaction parameters were widely varied. As the nnn interaction was enhanced, the soliton velocity increased and the soliton energy decreased. The results were compared with those of 1D, 2D and 3D crystals obtained previously. Discussions and remarks are presented for these results.