Antiferroelectric-to-ferroelectric transitions in squaric acid are simulated by computationally applying a static electric field. Depending on the direction of the electric field, two different metastable ferroelectric (and piezoelectric) phases have been found. One of them corresponds to the experimentally confirmed phase, whereas the other is an optimally polarized phase. The structural details of these phases have been determined as a function of the electric field. The spontaneous polarization values of the phases are 14.5 and 20.5 $\mu \mathrm{C}$/${\mathrm{cm}}^2$, respectively, and are relatively high among those of the existing organic ferroelectrics.

• Received 8 February 2018
• Revised 3 April 2018

DOI:https://doi.org/10.1103/PhysRevB.97.184102