Molecular Origin of Positive and Negative Electromechanical Response in Hydrogen-Bonded Systems

Hydrogen bonds, ubiquitous in organic and biological materials, involve weak electrostatic interactions, which can geometrically distort in response to an applied electric field. This electromechanical response is a key component in a range of piezoelectric materials in applications including energy harvesting and sensing. In this work, we apply electronic structure methods across a combinatorial pool of over 218 hydrogen-bonded dimers to examine the connection between the electrostatics, potential energy surface, and the resulting electromechanical response. Strikingly, while inorganic piezomaterials typically exhibit positive piezo response, expanding in response to an applied field, we find that hydrogen bonding interactions instead typically exhibit negative response, contracting due to the local electrostatics between the hydrogen bond donor and acceptor functional groups.