ORIENTATIONAL L, D AND POLARIZATION DEFECTS AS COUPLED QUANTUM NONLINEAR EXCITATIONS IN HYDROGEN-BONDED SYSTEMS

We have studied the proton structure and energy of a D (or an L) defec t in a zig-zag hydrogen-bonded system. It is shown that the extra (or missing) proton lowers its energy by creating a polarisation defect to which it is coupled. We used a quantum description with intrasite and intersite tunneling, while taking into account the polarisation state of the neighboring bonds. In the case of a localised defect a compari son is made with classical double-well potential results.