Two-Dimensional Sine-Gordon Lattice with Fixed Winding Number: A Molecular-Dynamics Study

抄録

With the use of molecular-dynamics technique, the power spectra of displacements have been calculated for the two-dimensional sine-Gordon lattice with fixed winding number at thermal equilibrium. A gap has been clearly observed in the excitation spectra at sufficiently low temperatures. With increasing temperature the finite spectra are found at the frequencies in the gap. These observed data are analyzed with the temperature-dependent spectra of domain-wall oscillations and optical phonons.