Soliton dynamics of hydrogen-bonded networks: A mechanism for proton conductivity

The dynamics of protons in hydrogen-bonded quasi one-dimensional networks is described in terms of a diatomic lattice model with a doubly periodic on-site potential. The discrete system is reduced to a continuum double sine-Gordon equation for the protonic part plus an easily solvable differential equation for the heavy part. Its two-component kink solitons correspond to the ionic and Bjerrum defects. The correct response of these solitonic defects to an externally applied electric field makes this system a suitable model for qualitative and quantitative description of the protonic conductivity in hydrogen-bonded networks.