Ab initio simulations of hydrogen-bonded ferroelectrics: collective tunneling and the origin of geometrical isotope effects

Abstract

Ab initio simulations that account for nuclear quantum effects have been used to examine the order-disorder transition in squaric acid, a prototypical H-bonded antiferroelectric crystal. Our simulations reproduce the >100 K difference in transition temperature observed upon deuteration as well as the strong geometrical isotope effect observed on intermolecular separations within the crystal. We find that collective transfer of protons along the H-bonding chains - facilitated by quantum mechanical tunneling - is critical to the order-disorder transition and the geometrical isotope effect. This sheds light on the origin of isotope effects and the importance of tunneling in squaric acid which likely extends to other H-bonded ferroelectrics.

5 pages, 4 figures

References in corpus (3)

• A Higher-Accuracy van der Waals Density Functional
• Deuteron Momentum Distribution in KD2HPO4
• Ab initio simulations of hydrogen-bonded ferroelectrics: collective tunneling and the origin of geometrical isotope effects

Cited by in corpus (6)

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• Ab initio simulations of hydrogen-bonded ferroelectrics: collective tunneling and the origin of geometrical isotope effects
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• Deconfinement of electric charges in hydrogen-bonded ferroelectrics
• Proton Quantum Effects in H${}_3$S Electronic Structure: A Multicomponent DFT study via Nuclear-Electronic Orbital Method