A simple shell model for the one-dimensional H-bonded ferroelectric CDP

R. MENCHÓN; F. TORRESI; J. LASAVE; S. KOVAL

Porto

Congreso; 13th European Meeting on Ferroelectricity; 2015

In this work we study the isotope effect and geometrical effect upon deuteration with a simple shell model for the 1D H-bonded Ferroelectric Cs$_2$H$_2$PO$_4$ (CDP) which belongs to the KDP-type family of compounds.We use a 1D novel shell model in which the inclusion of the correlation between protons and oxygen polarizabilities allows us to consider in a simple and physical way the ice rules that are relevant to the system.The model is adjusted to density functional theory (DFT) calculations of CDP performed with the Quantum Espresso programand reproduces the ab initio energy profiles of different single and collective moves as well as their dependence with H-bond length.We perform classical and path integral Monte Carlo simulations to study the large geometrical effect present in this compound. We find a strengthening of the O-D bond and an increase in the O-O distance upon deuteration which is compatible with experiments.This simple atomistic model will allow us to simulate the phase transition in large systems and to gain deeper knowledge of the microscopic mechanism behind the Ferroelectric phase transition in CDP and related compounds.