A SIMPLE-MODEL FOR FERROELECTRICS AND ANTIFERROELECTRICS WITH ISOLATED HYDROGEN-BONDS

In some substances hydrogen bonds are considered to play an important role in their ferroelectric or antiferroelectric properties. These materials usually have large isotope effects in phase transition temperatures which are expected to be closely related to the natures of hydrogen bonds. Our model describes the quantum mechanics of the electron and the Proton (or deuteron) in the 0-dimensional hydrogen bond which does not form networks in the crystal structure. By a variational analyses of this model based on the adiabatic approximation, we can reproduce characteristic features of the behaviors of a proton and a deuteron in hydrogen bonds.