Running VASP Calculations to find ferroelectric properties of

hydrogen bonded co-crystals

Voiceover

Presenter(s)

Oscar Gonzalez

Abstract or Description

Ferroelectricity is a property some materials share that allows their

polarization to invert when affected by an external electric field. Organic

ferroelectrics have high potential for utility for future electronics,

including bio-compatible solid-state memories. In this work the polar

crystal structures for two organic co-crystalline compounds are studied

computationally. The two compounds, 2-amino-4-methylpyridinium 4-

nitrophenolate 4-nitrophenol (BORGEW) and Isonicotinohydrazide 4-

aminosalicylic acid (URUDER) were uncovered as potentially

ferroelectric during a prior database search. These co-crystals may

exhibit sizable ferroelectric properties needed for practical application.

The unit cell structures for both co-crystalline compounds were used to

create averages and supercells with both polar forms. The original

crystal structures, and supercells were subjected to calculations using

Density Functional , to relax and optimize the unit cell geometry.

Artificial average unit cells were created as by averaging geometries of

opposite polar forms; these cells were not optimized but were subjected

to single point calculations. The Berry Phase method was used to

determine the difference in polarization between polar and non-polar

forms, which can be used to predict the experimental degree of

polarization possible during ferroelectric transition. Initial values for

difference in polarization predicted are quite high, and further

refinement of the systems is in progress.

Mentor

Dr. Kimberley Cousins