Strong 2D Polarization in Cocrystal of P-Benzoquinone Monoimine and Croconic Acid Joseph Mancuso, Thomas Wojtal, Daniel P. Miller Optimal to Unit Cell 1 Transition 1 0.8 0.6 0.4 0.2 0
2.51D
0
2
Optimal to Unit Cell 2 Transition
5.01D
4
6
0.00DReaction Coordinate
Figure 4. Energy and Polarization Changes Transitioning from Optimal to Unit Cell 1
Computational Methods: •ADF and VASP software packages used for calculations, Avogadro used for visualization
Optimal to Unit Cell 3 Transition
Relative energy (eV)
•revPBE-D3 functional and dispersion correction •The TZP basis set and plane-wave energy cutoff of 500 eV used in ADF and VASP, respectively. •Performed geometry optimizations that involved relaxing the unit cell along with every atom, unless constraints were necessary to create a proton transferred structure. •Single point calculations were done on the optimized structures and linearly interpolated structures generated to determine the change in polarization and the potential energy landscape of the proton transfers.
Results:
Conclusions: 1. 2.
2 1
0.0407D
0.5 0 0
0.00D
2
4
0.6
0.387D
0.4
0.187D
0.2 0 0
0.00D
2
4
6
Reaction Coordinate
Figure 5. Energy and Polarization Changes Transitioning from Optimal to Unit Cell 2
Optimal to Unit Cell 4 Transition
0.0814D
1.5
Relative energy (eV)
Relative energy (eV)
application of an electrical field. These materials have become a mainstay in RAM for computers, capacitors for ultrasound machines, and infrared cameras.1 Broadly there are three different types of ferroelectrics: charge displacement, proton transfer, and order/disorder materials, with the proton transfer type examined herein. Croconic acid (CA) is a known ferroelectric in its crystalline form and this discovery has renewed the interest in organic ferroelectric materials due to their less toxic and more affordable nature.2 Very large polarization shifts (up to 13.30D) can be induced through proton transfer in a cocrystal of CA and a quinonoid zwitterion, PZI.3 Therefore, it was hypothesized that a cocrystal of CA and p-benzoquinone monoimine (PBQMI) would be a potent ferroelectric cocrystal due to the similar chemistry PBQMI shares with the quinonoid zwitterion (Figure 1).
6
Reaction Coordinate
Figure 6. Energy and Polarization Changes Transitioning from Optimal to Unit Cell 5
Relative energy (eV)
Introduction: Ferroelectric materials have an inducible polarization that can be reversed by
0.6 0.4
0.00616D
0.2
0.0142D
0 0
2
4
6
0.00D Reaction Coordinate Figure 7. Energy and Polarization Changes Transitioning from Optimal to Unit Cell 7
CA forms a thermodynamically favorable cocrystal with PBQMI The CA-PBQMI cocrystal has a local minimum that induces a large polarization change of 5.01D (Optimal to Unit Cell 1), that could transfer to its mirror image, which would bring the polarization change to 10.02D.
References: 1. J.F. Scott (2000). Ferroelectric Memories. Springer. 2. Horiuchi, S; Tokunaga, Y; Giovannetti, G; Picozzi, S; Itoh, H; Shimano, R; Kumai, R; Tokura, Y. Above-roomtemperature ferroelectricity in a single-component molecular crystal. Nature 2010 463, 789-792. 3. Miller, D; Interactions at the Surface-Adsorbate Interface: An Outlook Through Computational Work. ProQuest Dissertations Publishing 2018 10928719.