Computer experiments on solitons in three-dimensional crystals with nearest-neighbor and next-nearest-neighbor atomic interactions

Molecular dynamics simulation was performed for three-dimensional (3D) cubic mass-spring model crystals. Anharmonic potential up to the fourth order was taken into account, and central forces between the nearest neighbor (nn) and the next nearest neighbor (nnn) atoms were considered. 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. As the nnn interaction was enhanced, the soliton velocity increased and the soliton energy decreased. The results were compared with those of ID and 2D crystals obtained previously. The increase of soliton velocity due to the enhanced min interaction was largest for ID crystals, and the decrease of soliton energy was smallest for 2D crystals. Discussions and remarks were presented for these results.