Isotope effect on high-pressure behavior of hydrogen-bonded crystals

Abstract

Abstract A variational correlated ground-state wave-function theory is applied to investigate the high-pressure deformation of hydrogen-bond potential. The effect of deuterium isotope substitution on the quantum-fluctuation-driven phenomena under high hydrostatic pressure is discussed. This model that simultaneously incorporates proton interaction energies and two-state quantum-mechanical tunneling has been applied to the interpretation of high-pressure data in terms of microscopic parameters of a compressed single hydrogen bond. The variation of tunnel splitting and proton interaction energies with pressure for deuterated and undeuterated hydrogen bonds is determined. The theory was employed for predicting and interpreting the pressure dependence of the phase transition temperature for KDP-like ferroelectrics and NQR-frequency coefficients for several deuterated and undeuterated crystals.