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

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.
Authors:
 [1] ;  [2]
  1. Science Institute, University of Iceland, Nordita, Stockholm, Sweden and University College London, London WC1E 6BT (United Kingdom)
  2. Thomas Young Centre, London Centre for Nanotechnology and Department of Chemistry, University College London, London WC1E 6BT (United Kingdom)
Publication Date:
OSTI Identifier:
22255244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 4; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CRYSTALS; DEUTERATION; FERROELECTRIC MATERIALS; HYDROGEN; ORDER-DISORDER TRANSFORMATIONS; SIMULATION; TRANSITION TEMPERATURE; TUNNEL EFFECT; TUNNELING