Nonlinear modes in helical lattices: Localized modes and kinks

Nonlinear modes in a 1-dimensional (1-D) helical lattice generated from a 1-D harmonic lattice with anisotropic interactions through geometrical constraints are studied. Depending on the degree of helicity and the anisotropy of interactions, obtained 1-D sine-plus-linear lattice equations exhibit two types of characteristic nonlinear modes, localized modes and kinks. Approximate analytical expressions for these two nonlinear modes are obtained and compared with the result obtained by numerical experiments for 1-D cases. The localized modes are shown to be robust against environmental fluctuations.