Effects of Dipole Moment on the Lattice Waves in One-Dimensional Dust Chain

Effects of dipole moment on the horizontal dust lattice waves in one-dimensional dust chain are investigated. The general dispersion relations are derived. The waves are sensitive to the direction of the dipole moment, which has an angle θ (0≤θ≤π) with respect to the vertical direction.
When the waves are self-excited, it is shown that the real part of frequency for longitudinal wave is increased, while it is decreased for the horizontal transverse wave with increasing θ. When the waves are externally exited, both the real and imaginary parts of wave number are decreased for the longitudinal and transverse waves with increasing θ.