NONLINEAR TRANSPORT IN HYDROGEN-BONDED CHAINS - FREE SOLITONIC EXCITATIONS

The longitudinal dynamics of protons in hydrogen-bonded chains is described with a one-component, one-dimensional model with a two-parameter doubly periodic on-site potential. Ionic and bonding defects are described as soliton solutions of this model. Their energy, momentum, mass, width, and charge are calculated in the continuum limit. Small-amplitude oscillating solutions of breather and envelope (or dark) soliton type have also been calculated. Exact kink-antikink solutions for the discrete system are obtained numerically using a very efficient technique based on well-known minimization procedures. Producing such accurate initial conditions, the defect dynamics are explored numerically for some realistic sets of the physical parameters of the model. The microscopic behavior of the proton interbond and intrabond transfer is thus well understood for the conservative, nondriven hydrogen-bonded chain.