Dynamics of dipolar molecular chains: from low excitations to soliton formation and classical chaotic dynamics

Abstract

We investigate the classical rotational dynamics of a one-dimensional chain of molecules with permanent electric dipole moments. The molecules are coupled via their dipolar interactions. Low excitations are studied by inspecting the first- and second-order perturbation terms away from the equilibrium position. In this regime, we find no sign of localized excitations (solitons). In the strong excitation (rotary) regime, the classical dynamics is found to be chaotic. For this case, we calculate the time-correlation functions and estimate the Kolmogorov entropy as well as the fractal dimension. In addition, thermodynamical properties are discussed. In the second part of this work, we propose a method for exciting controllably the dipoles by means of a static electric field and a linear polarized, single-mode laser pulse. In the presence of external fields, we study the excitation propagation dynamics in the chain. As a function of the properties of the applied fields (strengths, frequency and pulse duration), we inspect the non-stationary solutions and identify the solitonic, the breather and the classical chaotic regimes as well as where nonlinear resonances emerge.